Question

1. What must be the value of k

in the function f(x) = x4 + x3 -
kx2 - 25x - 12 so that (x - 4) is a
factor.
a. -12
b. -13
c. 13
d. 12

Answer 1

C

Explanation:

x - 4 is a factor means x = 4 gives f(x) = 0

`x^4+x^3-kx^2-25x-12\\4^4+4^3-k.4^2-25.4-12=0\\256+64-16k-100-12=0\\16k=320-112\\16k=208\\k=13`