Question

Knowing that –3 is the root of P (x) = x³ + 4x² - ax + 1, calculate the value of a and mark the correct answer.

Answer 1

value of a is -3.33

or in fraction -10/3

Explanation:

If -3 is the root of P(x)

then

P(-3) = 0

then we substitute -3 in place of x in the given equation

P (x) = x³ + 4x² - ax + 1

P (-3) = -3³ + 4*-3² - a(-3) + 1

=> 0 = -27 + 36 + 3a + 1

=> 0 = 10 + 3a

=> 3a = -10

=> a = -10/3 = -3.33

Thus, value of a is -3.33