Question

For what value of k,-4 is a zero of the polynomial $x^{2}-x-(2k+2)$

Answer 1

SOLUTION :  

Let f(x) = x² - x - (2k +2)

Since, x = -4 is a zero of polynomial f(x).

Therefore, f(-4) = 0

f(x) = x² - x - (2k + 2)

(-4)² -( -4) -(2k + 2) = 0

16 + 4 -2k -2 = 0

20 - 2 - 2k = 0

18 - 2k = 0

18 = 2k  

k = 18/2

k = 9

Hence, the value of k is 9.

HOPE THIS ANSWER WILL HELP YOU..

Answer 2

f(x)=0

Putting in place of x=-4

f(x)=x²-x-(2k+2)
0=(-4)²-(-4)-(2k+2)
0=16+4-2k-2
0=18-2k
-18=-2k
18=2k
18/2=k
9=k