Question

Z^2 + 9z - 90 = (z -6) (z + )
Complete.

Answer 1

(z - 6)(z + 15)

Explanation:

Given

z² + 9z - 90

Consider the factors of the constant term (- 90) which sum to give the coefficient of the z- term (+ 9)

The factors are - 6 and + 15, since

- 6 × 15 = - 90 and - 6 + 15 = + 9, hence

z² + 9z - 90 = (z - 6)(z + 15)