<p>If one solution to x^2 - kx-8=0 is x=-k, what are the possible values of k?</p>
<p>a. -4,4
b. -2,2
c. 0,2</p>
<p>B.</p>
<p>Begin by substituting -k in for each x value. This yields:
(-k)^2 - k*(-k) - 8 = 0</p>
<p>You can simplify this to:
k^2 + k^2 = 8
And again to:
2k^2 = 8
Divide by 2:
k^2 = 4
Square Root both sides:
k = ±2
The plus minus is need when you use square root like this.
Therefore, the answer is -2,2.</p>
<p>thanks!!!</p>