Question

Factor this trinomial.

x^2 - 9x + 20
A. (x - 2)(x - 10)
B. (x - 4)(x - 5)
C. (x-2)(x + 10)
D. (x-4)(x + 5)

Answer 1

b

Explanation:

factorise

(x²-5x) - (4x+20)

x(x-5) -4( x-5)

(x-4) (x-5)

Answer 2

Answer: (x - 4) (x - 5)

So since the last number in the trinomial (20) is positive, and the second number (-9x) is negative, this means both of the factors will be negative, so that means the answer is NOT C or D.

So you have to find two numbers that multiply to make 20 (last number) and that add to make -9 (second number).

So the answer is B, and have -4 and -5 because you multiply and get positive 20, and add and get -9.