Find the Function f(x)=3x^2-4

$f (x) = 3 x^{2} - 4$

The function $F (x)$ can be found by evaluating the indefinite integral of the derivative $f (x)$ .

$F (x) = \int f (x) d x$

Split the single integral into multiple integrals.

$\int 3 x^{2} d x + \int - 4 d x$

Since $3$ is constant with respect to $x$ , move $3$ out of the integral.

$3 \int x^{2} d x + \int - 4 d x$

By the Power Rule, the integral of $x^{2}$ with respect to $x$ is $\frac{1}{3} x^{3}$ .

$3 (\frac{1}{3} x^{3} + C) + \int - 4 d x$

Apply the constant rule.

$3 (\frac{1}{3} x^{3} + C) - 4 x + C$

Simplify.

Combine $\frac{1}{3}$ and $x^{3}$ .

$3 (\frac{x^{3}}{3} + C) - 4 x + C$

Simplify.

$x^{3} - 4 x + C$

The function $F$ if derived from the integral of the derivative of the function. This is valid by the fundamental theorem of calculus.

$F (x) = x^{3} - 4 x + C$