I have found the intersection points between the curves to find the interval but even while doing it with respect to x or to y, my answer is always wrong. please help
HINT: Draw a diagram indicating the required area bounded by $y=4$, $y=2\sqrt x$ & $y=3-x$. Divide the bounded region into two smaller regions, then one should get area bounded $$=\frac{1}{2}(2\times 2)+\left(3\times 4-\int_{1}^{4}2\sqrt x\ dx\right) $$
HINT: Draw a diagram indicating the required area bounded by $y=4$, $y=2\sqrt x$ & $y=3-x$. Divide the bounded region into two smaller regions, then one should get area bounded $$=\frac{1}{2}(2\times 2)+\left(3\times 4-\int_{1}^{4}2\sqrt x\ dx\right) $$