Question

How do you find the product `(7z^2+5y^2)(7z^2-5y^2)`?

Answer 1

`49z^4 - 25y^4`

Explanation:

`(a+b)(a-b) = a^2 - b^2`

In this case, `a = 7z^2` and `b=5y^2`

`a^2 = 7^2 * (z^2)^2 = 49z^4`

`b^2 = 5^2 * (y^2)^2 = 25y^4`

`a^2 - b^2 = 49z^4 - 25y^4`