Question

Solve: $\frac{d}{dx}7x$

Answer 1

According to first Principle method

$f^{\prime }\left(x\right)=\frac{f(x+h)-f\left(x\right)}{h}$

Now, for finding

$\frac{d}{dx}7x$

Let $f\left(x\right)=7x$

Hence, $f^{\prime }\left(x\right)={lim}_{h\to 0}\frac{7(x+h)-7x}{h}={lim}_{h\to 0}\frac{7h}{h}=7$