Question

Find the roots of the polynomial equation.
x^2 + x - 72 = 0

A. 9 and –8

B. –6 and 6

C. –2 and 16

D. –9 and 8

Answer 1

As this is a quadratic function, it could be solved by using the quadratic formula or through factorisation. As factorisation is simpler to type, x^2 + x - 72 = (x - 8) (x + 9) =0.
From here, let x - 8 = 0 and x + 9 = 0. Hence, x = 8 and x = -9. This answer is confirmed by resubbing these values into the quadratic to verify. Hence, the answer is D