please help:(

$\dfrac{d}{dx} \displaystyle \int_{a(x)}^{b(x)}f(t)~dt = \\ f(b(x))\dfrac{db}{dx} - f(a(x))\dfrac{da}{dx}$

$\dfrac{d}{dx} \displaystyle \int_3^{x^2}\dfrac{\sqrt{1+2t}}{t}~dt = \\ \dfrac{\sqrt{1+2x^2}}{x^2}\cdot 2x - \dfrac{\sqrt{1+2(3)}}{3}\cdot 0 = \\ \dfrac{2\sqrt{1+2x^2}}{x}$