Question

For what values of $$x$$ are the numbers $$-\frac{2}{7}, x, -\frac{7}{2}$$ in G.P.?

Options

• 0, 1

• 0, –1

• –1, 1

• –2, 2

Answer 1

–1, 1

Explanation:

For three terms in a G.P., the square of the middle term equals the product of the outer terms. Thus, $$x^2 = \left(-\frac27\right)\left(-\frac72\right) = 1$$, so $$x = \pm1$$.