Question

Which of the following is a polynomial with rootsnegative square root of 5, square root of 5, and 3

Answer 1

P(x) = x³ - 3x² - 5x + 15

Explanation:

∵ The roots of the polynomial are -√5 , √5 , 3

∴ The polynomial has 3 factors:

(x - √5) , (x + √5) , (x - 3)

∴ P(x) = (x - √5)(x + √5)(x - 3)

= (x² + √5x - √5x - 5)(x - 3)

= (x² - 5)(x - 3) = x³ - 3x² - 5x + 15

∴ P(x) = x³ - 3x² - 5x + 15