Question

How do you multiply `(x - 7) (x + 7)`?

Answer 1

`=color(blue)(x^2-49`

Explanation:

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

The same property can be applied to the expression `(x-7)(x+7)` where `color(blue)(a)=x, color(blue)(b)=7`

So,
`(x-7)(x+7) = x^2-7^2`

`=color(blue)(x^2-49`