Question

x³ + 3x² - 18x - 40 factorise​

Answer 1

Answer:

Given :-

➪ x³ + 3x² - 18x - 40

Solution :-

➪ x³ + 3x² - 18x - 40

➭ x³ - 4x² + 7x² - 28x + 10x - 40

➭ x²(x - 4) + 7x(x - 4) + 10(x - 4)

➭ (x - 4) (x² + 7x + 10)

➭ (x - 4) {x² + (5 + 2)x + 10}

➭ (x - 4) {x² + 5x + 2x + 10}

➭ (x - 4) {x(x + 5) + 2(x + 5)}

➭ (x - 4) (x + 5) (x + 2)

∴ The value of x³ + 3x² - 18x - 40 is

(x - 4) (x + 5) (x + 2)