The functions f(x, t) and F(x) are defined by f(x, t) = e-xt and \(F(x)=\int_0^x f(x, t) dt.\) Then \(\frac{dF}{dx}=\)
1
\(f(x, t) + \int_0^x \frac{\partial f(x, t)}{\partial x}dt\)
2
\(f(x, x) + \int_0^x \frac{\partial f(x, t)}{\partial x}dt\)
3
\(f(0,0) + \int_0^x \frac{\partial f(x, t)}{\partial x}dt\)
4
\(f(t, t) + \int_0^x \frac{\partial f(x, t)}{\partial x}dt\)