$2 \cdot 135$ The root of the equation $2 \sqrt{x}+2 x^{-\frac{1}{2}}=5$ can be found by solving which of the following equations?
(A) $16 x^{2}-92 x+1=0$.
(B) $4 x^{2}-25 x+4=0$.
(C) $4 x^{2}-17 x+4=0$.
(D) $2 x^{2}-21 x+2=0$.
(E) $4 x^{2}-25 x-4=0$.
(5th American High School Mathematics Examination, 1954)
[Sol] Squaring both sides of the equation, we get $4\left(x+\frac{1}{x}+2\right)=25$, which simplifies to $4 x^{2}-17 x+4=0$.
Therefore, the answer is $(C)$.