Answer:
B. -8
Step-by-step explanation:
[tex]\text{If}\ a,\ b,\ c\ \text{is a geometric sequence, then}\ (a)(c)=b^2.\\\\\text{We have}\ x,\ 2,\ -\dfrac{1}{2}.\ \text{Substitute:}\\\\(x)\left(-\dfrac{1}{2}\right)=2^2\\\\-\dfrac{1}{2}x=4\qquad\text{multiply both sides by (-2)}\\\\x=-8[/tex]
