# How do you find the product (y+4)(y-8)?

Dec 1, 2016

$y = - 4 \mathmr{and} 8$

#### Explanation:

$\left(y + 4\right) \left(y - 8\right)$

${y}^{2} - 8 y + 4 y - 32$

This is a quadratic equation (because of the power of 2), so we will have to use the quadratic formula which is:

$a x + b y + c = 0$

So

${y}^{2} - 4 y - 32 = 0$

So basically, now we know the quadratic equation, we can say:

$\left(y + 4\right) \left(y - 8\right) = 0$

$y = - 4$

$y = 8$

because if one or the other equals to 0, then multiplying it with any number makes it 0.

Dec 1, 2016

The question only askes for the product which is:

${y}^{2} - 4 y - 32$

#### Explanation:

$\textcolor{b l u e}{\left(y + 4\right)} \textcolor{g r e e n}{\left(y - 8\right)}$

Multiply everything in the right hand side bracket by everything in the left one.

color(blue)(ycolor(green)((y-8))" "+" "4color(green)((y-8))

${y}^{2} - 8 y \text{ "+" } 4 y - 32$

${y}^{2} - 4 y - 32$