Question

Without actual division show that f(x) = (x3 − 3x2 − 13x + 15) is exactly divisible by g(x) = (x2 + 2x − 3).

Answer 1

see explanation

Explanation:

Note that the sum of the coefficients of g(x)

1 + 2 - 3 = 0

Hence x = 1 is a root of g(x) and (x - 1) is a factor

Note the sum of the coefficients of f(x)

1 - 3 - 13 + 15 = 0

hence x = 1 is a root of f(x) and (x - 1) is a factor

Since (x - 1) is a factor of both

Then f(x) is also divisible by x² + 2x - 3