Question

What is the factored form of the following expression? x2 – x – 42

Answer 1

\(\Large \color{MidnightBlue}{\Rightarrow x^2 - 7x +6x - 42 }\)
\(\Large \color{MidnightBlue}{\Rightarrow x(x - 7) + 6(x - 7) }\)
\(\Large \color{MidnightBlue}{\Rightarrow (x + 6)(x - 7) }\)

Answer 2

to factorise:

multiply your constant by the coefficient of x²

1 x -42=-42

you want two numbers that multiply to give -42 but add to give the coefficient of x

+6 and -7 work for this

replace the -x with +6x-7x


x²+6x-7x-42

take out the common factor of x²+6

x(x+6)
do the same for -7x-42
-7(x+6)

now you have

x(x+6)-7(x+6)

your factorised form is
(x-7)(x+6)

Answer 3

A. (x – 7)(x + 6)
I got this correct on my test.