If 4x + 1/x = 5, x 0 , then the value of 5x4x^2 + 10x + 1 is?

Answer: Option B

$$\begin{array}{rl}& \frac{5x}{4x^2+10x+1}\\ & =\frac{5x}{x\left(4x+10+\frac{1}{x}\right)}\\ & =\frac{5}{4x+\frac{1}{x}+10}\\ & =\frac{5}{5+10}\\ & =\frac{5}{15}\\ & =\frac{1}{3}\end{array}$$