Question

The value of k for which x - 1 is a factor of $4x^3+3x^2$ - 4x + k, is

• A. 3
• B. 1
• C. -2
• D. -3

Answer 1

The correct option is D

-3

x - 1 is a factor of f(x) = $4x^3+3x^2$ - 4x + k

Let x - 1 = 0, then x =1

f(1) = $4(1{)}^3+3(1{)}^2-4\times$ 1 + k = 4 +3 - 4 + k = 3 + k

$\therefore$ x -1 is a factor of f(x)

$\therefore$ Remainder = 0

$\therefore$ 3+k = 0 $\Rightarrow$ k=-3