Question

(x^4+y^5)(x^4-y^5)... same as my last question, I can work it out with numbers but just with variables throws me off....please help!!!!

Answer 1

Multiplying?

Answer 2

yes

Answer 3

Are you familiar with the factored form of a 'difference of squares?"

Answer 4

no not at all

Answer 5

ok, let's look at something simpler then..

What would you get if you multiplied \((a+b)(a-b)?\)

Answer 6

a^2-b^2 ??

Answer 7

Right, so you see you have a difference of squares there: one square (a^2) minus another square (b^2). In your above example, you have something very similar.

Answer 8

So do the same as with (a+b)(a-b), but now a = x^4 and b = y^5.

Answer 9

but what about the exponents how do I work those

Answer 10

When you multiplied a*a = a^2, it was really a^1 * a^1 = a^2.
If you multiply powers of the same base, you add the exponents, so for x^4 * x^4, it is x^(4+4). Understand?

Answer 11

I think...ok... so I wouldn't add the two 4's???