# How do you write the function in standard form y=-(x+3)(x-4)?

Sep 3, 2016

$- {x}^{2} + x + 12$

#### Explanation:

We must ensure that each term in the 2nd bracket is multiplied by each term in the 1st bracket.
This can be done as follows. Leaving the - outside the brackets until after multiplication.

$\left(\textcolor{red}{x + 3}\right) \left(x - 4\right) = \textcolor{red}{x} \left(x - 4\right) \textcolor{red}{+ 3} \left(x - 4\right)$

now distribute the brackets and collect like terms.

$= {x}^{2} - 4 x + 3 x - 12 = {x}^{2} - x - 12$

now go back and do multiplication by - 1

$\Rightarrow - \left({x}^{2} - x - 12\right) = - {x}^{2} + x + 12$