The Purplemath Forums

This is an example of an expression. Expressions can have numbers, variables and symbols (like add, subtract, multiply, divide, parentheses, etc). The difference between an expression and an equation is that an equation has an equal sign in it. If this were an equation, you would need to solve it an...

To answer where the B term came from in the expression ax^2+bx+c, are you familiar with the foil method of multipying a binomial by a binomial? If not, it's an acronymn that stands for First, Outer, Inner, Last. First: multilipy each of the first terms in both parentheses. This gives you (4x)(2x) = ...

Julia, actually you got pretty far since you got to y^3 = -4. I think the confusion lies in your thinking that you can't take the cube root of a negative number. If your problem were y^3 = -8 then to find the cube root, think of what number cubed gives you a -8 and that would be -2 since (-2)(-2)(-2...

Perhaps it's best to rewrite the question as: how much of each fabric must be used to get one pound of the mixed fabric? One thing we can start with is the fact that n=p since the amt. of nylon = amt. of polyester. Then, (cost of C)(amt.of C) + (cost of P)(amt. of P) + (cost of N)(amt. of N) = (cost...

MathRaven, It helps if you have a list of identities to choose from. I started with sin 4x = 2 sin 3x cos x - sin 2x and then used sin 3x = (sin x) (-1 + 4cos^2x), so using this substitution we get = 2 [(sin x) (-1 + 4cos^2x)]cos x - sin 2x = 2[sinx cos x (-1 + 4cos^2x)] - sin 2x = 2 [ -sinx cosx + ...

Marie, The way you stated the problem, the possibilites are endless and, of course, nothing a person should ever consider. But, if you said that the person wanted $50,000 in 50's and 100's, even so, you can see that there are many, many ways that you can come up with the $50,000. In order to come up...

:nono: You don't want to "plod through various possibilities until you happen upon a solution". That would take some time. You want to solve the problem by substituting the ? with an x. This gives: (76-x)/2 = 41. Then the first thing to do is to get rid of the denominator. This can be done...