Question

Find the value of polynomial 3x2 + 9x - 5 at x = 7​

Answer 1

Step-by-step explanation:

Consider the equation

x3 – 3x2 – 9x – 5…………………..(1)

The equation can be simplified as

x3 + x2 – 4x2 – 4x – 5x – 5

x2 (x + 1) – 4x (x + 1) -5(x + 1)

(x + 1)(x2 – 4x – 5)

(x + 1)(x2 – 5x + x – 5)

(x + 1) (x – 5)(x + 1)

∴ (x + 1), (x – 5) and (x + 1) are factors of given polynomial.