Question

Determine the value of A so that x-1 is a factor of 2x^3 +x^2+2Ax+4

Answer 1

When a polynomial f(x) is divided by ax + b and f(a/b) = 0, ax - b is a factor of f(x).

Let 2x³ + x² + 2Ax + 4 be f(x).

f(1) = 0

Substitute x = 1 into the equation.

2(1)³ + (1)² + 2A(1) + 4 = 0

2 + 1 + 2A + 4 = 0

2A = -7

A = -7/2