Question

Solve by factorisation
2x2 + 3x - 20 = 0

Answer 1

ac value is 2(-20) = -40
So what multiply to give -40 and add to give 3?

-5 and 8

So, write

2x^2 +8x-5x-20=0
then factorise

2x(x+4) and -5(x+4)

(2x-5)(x+4)
2 values of x: 2.5 and -4