Question

Using the remainder Theorem, factorise the expression 3x³ + 10x² + x – 6. Hence, solve the equation 3x³ + 10x² + x – 6=0

Answer 1

Let f(x) = 3x³ + 10x² + x − 6

For x = − 1,

f(x) = f(−1) = 3(−1)³ + 10(−1)² + (−1) − 6 = −3 + 10 − 1 − 6 = 0

Hence, (x + 1) is a factor of f(x).