A new study has found that up to half of people who think they have a penicillin "allergy" can still receive the drug, and other antibiotics with similar structures, without any negative reactions to the meds. Why? Because they're not really allergic, doctors say.

C For Chemistry delves into the chemistry of science experiments. This chemist knows what he's talking about. These chemistry experiments are not only fun, but very educational for all of those interested in scientific chemical reactions and properties.

This tutorial explains how you can divide integers. Dividing integers is similar to multiplying integers. A positive divided by a positive gives you a negative number. A negative divided by a negative gives you a positive number. And a positive divided by a negative, or a negative divided by a positive, will results in a number. Some examples: -15 divided by 3. In this problem we're dealing with a negative divided by a positive. So, the answer will be negative. The answer is -5. Another examp...

How to subtract positive and negative integers: There are four types of subtraction:

In this Math Made Easy tutorial the author shows how to subtract positive and negative numbers. He says that because of the numerous combination of positive and negative numbers it adds to a lot of confusion. Now he shows a trick of how to add positive numbers to negative numbers showing that it's equivalent to subtracting the negative number from the positive number. He shows that if you want to subtract a negative number from a positive number we should actually cancel all the signs and the...

Remember the old days when we used to use film negatives? You'd use them to create slides or even prints from the local photo lab. CNET shows you how to updates all your old photo prints, slides and negatives into digital copies on your computer using a multifunction printer, which most nowadays have slide and negative scanners built right in.

Taking the negative of an image in photography brings out its major contours and creates a powerful graphic contrast between white and black. The same sort of effect happens when you construct a card using only the "negatives" and no other colors.

Chemistry can be very fun when you create different kinds of reactions between elements. Note that caution should be employed to not harm yourself while performing these reactions. Ammonium Tricynate reacts with barium hydroxide octahydrate in endothermic form. Endothermic reactions are those which absorb heat from the surroundings during the reactions as opposed to exothermic reactions which produce a lot of heat during the reaction. When endothermic reaction occurs, depending up on the inte...

Multiplying positive and negative numbers may seem confusing. However, in this math tutorial, multiplying numbers with different or same signs is made easy and eliminates all confusion. The narrator of the video explains the key rules to remember when dealing with the possible combination of positive and negative numbers. The video breaks it down to two key rules. When you have a negative and a positive number; the result will always be negative. When you are given two numbers that have the s...

Want to simplify a rational expression with a negative exponent? It's easy once you know how. Learn how it's done with this free video algebra lesson. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just study for that next big test).

Doug Simms gives a demonstration of multiplying fraction in a simple and easy manner. The simplest problems have proper fractions to be multiplied by proper fractions, and the answer can be arrived at by simply multiplying the numerator (upper value) of one fraction with the numerator of the other, carrying out the same operation with the denominators (lower values) of the two fractions, and finally, reducing the resultant fraction by a common factor, if any. Doug also gives three other examp...

This video tutorial is in the Education category which will show you how to solve single-step inequalities using the reciprocal. Let's solve the problem "negative 5/2 X is less than equal to negative 1/5". To solve for "X", we need to get rid of "negative 5/2". To do that, we multiply both sides of the inequality by the reciprocal of 5/2 and we need to keep the negative sign also. So, we multiply both sides by "negative 2/5". Whenever we multiply a negative to both sides of an inequality, the...

This shows the process of making a positive image on clear glass; traditionally, this would be called an Ambrotype. Here, it is a little bit overexposed to get a "soft negative" or a negative that can be used with modern silver paper (printing). Learn how to make a glass positive or soft negative picture with the Collodion printing technique by watching this video photography tutorial.

Have you ever found something funny in an awkward situation? When you feel a laugh coming, it can sometimes be hard to avoid. Check out these steps to stop your laugh before it gets you in trouble.

This video helps us understand the organic molecules and elimination reaction. Take some sugar in a beaker. Sugar has 12 carbon atoms, 22 hydrogen atoms and 11 atoms of oxygen. The sulphuric acid is poured into the sugar and the color change is observed. The color of the sugar gradually changes into black. The sulphuric acid causes an exothermic reaction which releases a large amount of sulphur dioxide gas. All the water (containing hydrogen and oxygen atoms) is eliminated out of the sugar du...

Not all inequalities are created equal. See how to solve three of the most common types with this free video algebra lesson, which discusses regular, negative and mixed-variable inequalities. From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test).

To solve simple algebraic expressions you have to use different properties. Distributive property is one among them. To apply distributive property in a algebraic expression multiply each term inside the parenthesis by the outside term. In this way you are distributing the outside term to all the inside terms and removing the parenthesis. Hence it is called distributive property. After multiplying add the like terms to simplify it further. Care should be taken to ensure the proper sign change...

In this algebra video the instructor shows how to work with complex numbers. When you have a positive number under the square root, you can easily find its value by writing it in the form of product of numbers, and then solving. That is, to find the square root of a positive number, you can find another number which multiplied by itself gives the original number. This new number becomes the square root of the original number. But when you are asked to find out the square root of a negative nu...

In this video the instructor shows how to multiply and divide integers. When multiplying or dividing two numbers if the signs of the two numbers are same then the sign of the result is a positive number. When multiplying or dividing two numbers if the signs of the two numbers are not same then the sign of the result is a negative number. So a positive number multiplied by a positive number gives a positive number. Similarly a negative number multiplied by a negative number gives a positive nu...

Materials needed: Altoid mint tin, 9 volt batter and connector, switch, 7812 voltage regulator, 12 volt computer fan, carbon filter and 2 pieces of screen. Wire the battery connectors. Solder all of the following: Negative connector to the switch, wire to the switch, ground wire of the voltage regulator to the middle wire, output for the 7812 to the fan, positive lead on the 9 volt connector to the input on the 7812 and the negative from the 7812 to the negative on the fan. Test. Put all the ...

Watch this video sequence and learn to use the negative form of adjectives to describe things in Japanese.

Watch this video to review the affirmative past tense and to learn how to conjugate Japanese verbs in the negative past tense.

This video shows the basics of multiplying integers. The main point that people can struggle with is the variation of signs. When multiplying integers you must always be aware of the positive and negative numbers. When you multiply two numbers that have the same signs, both positive or both negative numbers, this will always generate a positive answer. If there is one positive and one negative number this will always lead to a negative answer. This video shows very basic problems of multiplyi...

Trying to increase your Japanese vocabulary? This video language lesson shows simple verbs in the negative form written in Japanese as well as English while the word is clearly pronounced. Follow along while watching this video Japanese language tutorial and learn how to read and say some basic verbs in the negative form.

Glowing substances have always held a powerful appeal to people, and making new ones can be a lucrative business. If you need some glow powder for a project of yours, watch this video to learn how to make DIY glow-in-the-dark powder out of normal household chemicals.

Watch this science video tutorial from Nurd Rage on how to dissolve glass with drain cleaner. They show you how to dissolve that glass with sodium hydroxide (drain cleaner).

This video explains the process of simplifying an algebraic expression with negative exponents. The video starts with an example of such an algebraic expression; the expression contains negative powers in both the numerator and denominator. The location of the negative exponents is first pointed out visually. Next, it is observed that there are like based or variables in both the numerator and denominator; however, it is explained that the numerator must first be expanded before the expressio...

In this video the instructor shows how to factor a trinomial with negative leading coefficient. Most of the students are confused when they have to factor a trinomial with a negative leading coefficient. But there are many ways to solve these kind of problems as shown in this video. One way you can do is that take out the greatest common factor (GCF) of -1 from the equation. So pulling the -1 gives you the original trinomial with all the signs of the terms changed. Now go on and factor the ne...

In this video, you will learn how to factor a simple trinomial. You will learn how to recognize a simple trinomial, and how to completely factor the trinomial. Also, it shows you how to factor square variables. The last example in the video explains how to factor out a negative first term. You can't just drop the negative and forget it is there. The instructor teaches you how to remove this negative, then reminds you not to forget to put the negative into your final answer.

This video shows us how to describe the situations that are opposite of the future perfect tense. Here it is shown how to describe the situations that did or did not happen in the past using would, have and past participle. He gives us 3 very good examples that are describing such situations. In these examples he describes a situation which happened in the past which is actually a negative and uses a fact that is described in the present tense to give the reason why that situation ended in a ...

View the absolute value of a number as its distance from zero. When you take the absolute value of a number, you always end up with a positive number (or zero). Whether the input was positive or negative (or zero), the output is always positive (or zero). For instance, | 3 | = 3, and | _3 | = 3 also. This property that both the positive and the negative become positive makes solving absolute-value equations a little tricky. But once you learn the "trick", they're not so bad. Let's start with ...

Need to learn how to divide positive and negative numbers? This instructional video will teach you the step by step process that will make you comprehend how to divide positive and negative integers. Just watch and follow along and you will soon be a wiz at tackling these kind of math equations. The simple steps will leave no question and you will be able to do any problem concerning the division of positive and negative integers and you will be better at math.

Love Microsoft Excel? This clip contains a tip that just might induce you to. With this free video tutorial from ExcelIsFun, the 4nd installment of his "YouTubers Love Excel 2007" or YTLE2k7 series of free video MS Excel lessons, you'll learn how to use conditional formatting to add red to negative numbers and green to positive numbers using a single True/False formula!

This will show you how to take negative afterimages to another level. By introducing a negative color photo and then immediately incorporating a black and white version of the same photo, you will perceive the black and white photo in full color (the way the color photo was meant to look). This can be done with any color photo, along with any photo editing program, like Adobe Photoshop.

Watch this science video tutorial from Nurd Rage on how to make a chemiluminescent reaction with home chemicals. Make a chemiluminescent singlet oxygen red light pulse from two simple chemicals almost anyone can buy: pool chlorine and hydrogen peroxide.

Lawrence Perez, from Saddleback College, and his assistant Charlie, give this pre-algebra lesson on adding negative numbers together. You'll learn the easiest way to do it, and maybe even freshen up on your subtracting skills. Don't waste your time in summer school, learn it here.

Lawrence Perez, from Saddleback College, and his assistant Charlie, give this pre-algebra lesson on subtracting negative numbers. Don't get confused with those minus symbols. Learn how to manage them correctly, and with ease.

In this episode learn to ask negative questions with "don't" followed by a verb and "to be" in the English language. This video is great for advanced, intermediate, and beginner learning to speak the English as a second language (ESL).

Tapping can help to free you from persistent or inappropriate negative emotions. Sometimes these emotions make sense. If someone close to you dies, or a relationship ends, you're going to feel sad. But sometimes we feel depressed for no good reason, or very angry with someone who hasn't really done anything to deserve it. You're the only judge of whether or not an emotion is appropriate or inappropriate.

Need to know how to multiply and divide negative numbers in basic math? From Ramanujan to calculus co-creator Gottfried Leibniz, many of the world's best and brightest mathematical minds have belonged to autodidacts. And, thanks to the Internet, it's easier than ever to follow in their footsteps (or just finish your homework or study for that next big test). With this installment from Internet pedagogical superstar Salman Khan's series of free math tutorials, you'll learn how to multiply and ...