Question

question attached

Answer 1

what am i doing wrong?

Answer 2

The second term, instead of being \[-(\sqrt x +3)\left({1 \over {2\sqrt x}} - {6 \over {x^3}}\right) \]should be \[(\sqrt x +3)\left({1 \over {2 \sqrt x}} - {10 \over {x^3}} \right)\]