Question

Multiply: (x - 4)(x + 5)​

Answer 1

(x-4)(x+5)

=x^2-4x+5x-20

=x^2+x-20

how it helps you....

Answer 2

You can also solve this question using identity (X+a)(X+b)=X^2+(a+b)X+ab

Here ,

X=X

a=-4

b=5

Using identity we got

X^2+(-4+5)X+(-4×5)

=X^2+X-20

------so, here is ur answer.--------