If x^2 + 1x^2 = 7/4 for x > 0 then what is the value of x^4 + 1x^4.

Answer: Option B

$$\begin{array}{rl}& \text{Given, }{x}^2+\frac{1}{x^2}=\frac{7}{4}\\ & \text{Squaring both sides, we get}\\ & x^4+\frac{1}{x^4}+2=\frac{49}{16}\\ & x^4+\frac{1}{x^4}=\frac{49}{16}-2\\ & x^4+\frac{1}{x^4}=\frac{49-32}{16}\\ & x^4+\frac{1}{x^4}=\frac{17}{16}\end{array}$$