Definite Integral of Constant Multiple of Real Function/Proof 1

Proof
Let $F$ be a primitive of $f$ on $\left[{a \,.\,.\, b}\right]$.

By Primitive of Constant Multiple of Function, $H = c F$ is a primitive of $c f$ on $\left[{a \,.\,.\, b}\right]$.

Hence by the Fundamental Theorem of Calculus: