Question

If $3x-\frac{1}{2x}=6$, then the value of $9x^2+\frac{1}{4x^2}$

• A. $36$
• B. $33$
• C. $30$
• D. $39$

Answer 1

The correct option is D $39$

Given that $3x-\frac{1}{2x}=6$

Squaring both sides, we get

$9x^2+\frac{1}{4x^2}-3=36$

We know the identity $a^2+b^2-2ab=(a-b{)}^2$

$9x^2+\frac{1}{4x^2}=39$