Question

Find the whole number such that 4 times the number subtracted from 3 times the square of number makes 15

Answer 1

Let 'x' be the whole number

According to the question,

3x² - 4x = 15 --------------------------------- (1)

⇒ 3x² - 4x - 15 = 0

using splitting the middle term method, we have

3x² - 9x + 5x - 15 = 0

⇒ 3x(x-3) + 5(x-3) = 0

⇒ (3x+5)(x-3) = 0

⇒ x = -5/3 or x =3

x = 3 satisfies eq(1), ∴ x=3 is the answer