# How do you use Part 1 of the Fundamental Theorem of Calculus to find the derivative of the function int sqrt (2 + sec 7t)?

$F \left(x\right) = \int f \left(t\right) \mathrm{dt}$
$\frac{d}{\mathrm{dx}} \left[\int f \left(t\right) \mathrm{dt}\right] = \frac{\cancel{d} {\cancel{F}}^{f} \left(x\right)}{\cancel{\mathrm{dx}}} = f \left(x\right)$
$\frac{d}{\mathrm{dx}} \left[\int \sqrt{2 + \sec 7 t} \mathrm{dt}\right] = \frac{\mathrm{dF} \left(x\right)}{\mathrm{dx}} = f \left(x\right) = \sqrt{2 + \sec 7 x}$