A6. For which $x$ is the sequence $\sqrt{x}, \sqrt{5 x-4}, 3 \sqrt{x}$ arithmetic?
(A) $x=1$
(B) $x=2$
(C) $x=4$
(D) $x=6$
(E) $x=\frac{1}{4}$

## II. PART
A6. The sequence is arithmetic if $3 \sqrt{x}-\sqrt{5 x-4}=\sqrt{5 x-4}-\sqrt{x}$. This implies $2 \sqrt{x}=$ $\sqrt{5 x-4}$, or $4 x=5 x-4$, hence $x=4$.

II. PART