Question

How do you factor `y^2-49`?

Answer 1

Rewrite the expression as a difference of two perfect squares.

Explanation:

You can factor the difference of two perfect squares by using the formula

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

You already have one perfect square, `y^2`, now all you have to do is write `49` as a perfect square, too.

`49 = 7 * 7 = 7^2`

The original expression now becomes

`y^2 - 7^2 = color(green)((y+7)(y-7))`