Question 871368
{{{-x^2+7x+18}}}

Multiply the first term and the third term

-18x^2

Split the middle term into two parts such that when you add the parts you get 7x and when you multiply them you get -18x^2

In this case the break up is 9 and- 2

9x-2x=7x

9x*-2x = -18x^2

Re write the trinomial

{{{-x^2+9x-2x+18}}}

factorize

-x(x-9)-2(x-9)

(x-9)(-x-2)