The constant multiple rule says that when a constant is multiplied by a function, the derivative is that same constant multiplied by the derivative of the function. This page focuses on using the constant multiple rule with power rule, trig derivatives, exponential derivatives, logarithmic derivatives, radicals, and fractions. These examples help build fluency with recognizing constants and applying derivative rules term by term.
Notes

Questions
Find the derivative of the function
\(\textbf{1)}\) \(f(x)=\displaystyle\frac{3}{x}\)
The answer is \(-\displaystyle\frac{3}{x^2}\)
\(\,\,\,\,\,f(x)=3x^{-1}\)
\(\,\,\,\,\,f'(x)=(-1)3x^{-1-1}\)
\(\,\,\,\,\,f'(x)=-3x^{-2}\)
\(\,\,\,\,\,f'(x)=-\displaystyle\frac{3}{x^2}\)
\(\,\,\,\,\,\)The answer is \(-\displaystyle\frac{3}{x^2}\)
\(\textbf{2)}\) \(f(x)=\displaystyle\frac{5}{x}\)
The derivative is \(f'(x)=-\displaystyle\frac{5}{x^2}\)
\(\,\,\,\,\,f(x)=5x^{-1}\)
\(\,\,\,\,\,f'(x)=(-1)5x^{-1-1}\)
\(\,\,\,\,\,f'(x)=-5x^{-2}\)
\(\,\,\,\,\,f'(x)=-\displaystyle\frac{5}{x^2}\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=-\displaystyle\frac{5}{x^2}\)
\(\textbf{3)}\) \(f(x)=\displaystyle\frac{1}{6}x^3\)
The derivative is \(f'(x)=\displaystyle\frac{x^2}{2}\)
\(\,\,\,\,\,f(x)=\displaystyle\frac{1}{6}x^3\)
\(\,\,\,\,\,f'(x)=3\cdot\displaystyle\frac{1}{6}x^{3-1}\)
\(\,\,\,\,\,f'(x)=\displaystyle\frac{1}{2}x^{2}\)
\(\,\,\,\,\,f'(x)=\displaystyle\frac{x^2}{2}\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=\displaystyle\frac{x^2}{2}\)
\(\textbf{4)}\) \(f(x)=5x^2\)
The derivative is \(f'(x)=10x\)
\(\,\,\,\,\,f(x)=5x^2\)
\(\,\,\,\,\,f'(x)=2 \cdot 5x^{2-1}\)
\(\,\,\,\,\,f'(x)=10x\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=10x\)
\(\textbf{5)}\) \(f(x)=5 \sin x\)
The derivative is \(f'(x)=5 \cos x\)
\(\,\,\,\,\,f(x)=5\sin x\)
\(\,\,\,\,\,\frac{d}{dx}(\sin x)=\cos x\)
\(\,\,\,\,\,f'(x)=5\cos x\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=5 \cos x\)
\(\textbf{6)}\) \(f(x)=-\displaystyle\frac{4}{x^2}\)
The derivative is \(f'(x)=\displaystyle\frac{8}{x^3}\)
\(\,\,\,\,\,f(x)=-\frac{4}{x^2}\)
\(\,\,\,\,\,f(x)=-4x^{-2}\)
\(\,\,\,\,\,f'(x)=-4(-2)x^{-3}\)
\(\,\,\,\,\,f'(x)=8x^{-3}\)
\(\,\,\,\,\,f'(x)=\displaystyle\frac{8}{x^3}\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=\displaystyle\frac{8}{x^3}\)
\(\textbf{7)}\) \(f(x)=3x^4-2x+8\)
The answer is \(12x^3-2\)
\(\,\,\,\,\,f(x)=3x^4-2x+8\)
\(\,\,\,\,\,f'(x)=3(4x^3)-2(1)+0\)
\(\,\,\,\,\,f'(x)=12x^3-2\)
\(\,\,\,\,\,\)The answer is \(12x^3-2\)
\(\textbf{8)}\) \(f(x)=7x^3\)
The derivative is \(f'(x)=21x^2\)
\(\,\,\,\,\,f(x)=7x^3\)
\(\,\,\,\,\,f'(x)=7(3x^2)\)
\(\,\,\,\,\,f'(x)=21x^2\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=21x^2\)
\(\textbf{9)}\) \(f(x)=-6x^5\)
The derivative is \(f'(x)=-30x^4\)
\(\,\,\,\,\,f(x)=-6x^5\)
\(\,\,\,\,\,f'(x)=-6(5x^4)\)
\(\,\,\,\,\,f'(x)=-30x^4\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=-30x^4\)
\(\textbf{10)}\) \(f(x)=\displaystyle\frac{2}{3}x^6\)
The derivative is \(f'(x)=4x^5\)
\(\,\,\,\,\,f(x)=\frac{2}{3}x^6\)
\(\,\,\,\,\,f'(x)=\frac{2}{3}(6x^5)\)
\(\,\,\,\,\,f'(x)=4x^5\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=4x^5\)
\(\textbf{11)}\) \(f(x)=-8\cos x\)
The derivative is \(f'(x)=8\sin x\)
\(\,\,\,\,\,f(x)=-8\cos x\)
\(\,\,\,\,\,\frac{d}{dx}(\cos x)=-\sin x\)
\(\,\,\,\,\,f'(x)=-8(-\sin x)\)
\(\,\,\,\,\,f'(x)=8\sin x\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=8\sin x\)
\(\textbf{12)}\) \(f(x)=9\tan x\)
The derivative is \(f'(x)=9\sec^2 x\)
\(\,\,\,\,\,f(x)=9\tan x\)
\(\,\,\,\,\,\frac{d}{dx}(\tan x)=\sec^2 x\)
\(\,\,\,\,\,f'(x)=9\sec^2 x\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=9\sec^2 x\)
\(\textbf{13)}\) \(f(x)=-2e^x\)
The derivative is \(f'(x)=-2e^x\)
\(\,\,\,\,\,f(x)=-2e^x\)
\(\,\,\,\,\,\frac{d}{dx}(e^x)=e^x\)
\(\,\,\,\,\,f'(x)=-2e^x\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=-2e^x\)
\(\textbf{14)}\) \(f(x)=4\ln x\)
The derivative is \(f'(x)=\displaystyle\frac{4}{x}\)
\(\,\,\,\,\,f(x)=4\ln x\)
\(\,\,\,\,\,\frac{d}{dx}(\ln x)=\frac{1}{x}\)
\(\,\,\,\,\,f'(x)=4\cdot\frac{1}{x}\)
\(\,\,\,\,\,f'(x)=\frac{4}{x}\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=\displaystyle\frac{4}{x}\)
\(\textbf{15)}\) \(f(x)=\displaystyle\frac{9}{\sqrt{x}}\)
The derivative is \(f'(x)=-\displaystyle\frac{9}{2x^{3/2}}\)
\(\,\,\,\,\,f(x)=\frac{9}{\sqrt{x}}\)
\(\,\,\,\,\,f(x)=9x^{-1/2}\)
\(\,\,\,\,\,f'(x)=9\left(-\frac{1}{2}\right)x^{-3/2}\)
\(\,\,\,\,\,f'(x)=-\frac{9}{2}x^{-3/2}\)
\(\,\,\,\,\,f'(x)=-\displaystyle\frac{9}{2x^{3/2}}\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=-\displaystyle\frac{9}{2x^{3/2}}\)
\(\textbf{16)}\) \(f(x)=-\displaystyle\frac{7}{x^3}\)
The derivative is \(f'(x)=\displaystyle\frac{21}{x^4}\)
\(\,\,\,\,\,f(x)=-\frac{7}{x^3}\)
\(\,\,\,\,\,f(x)=-7x^{-3}\)
\(\,\,\,\,\,f'(x)=-7(-3)x^{-4}\)
\(\,\,\,\,\,f'(x)=21x^{-4}\)
\(\,\,\,\,\,f'(x)=\displaystyle\frac{21}{x^4}\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=\displaystyle\frac{21}{x^4}\)
\(\textbf{17)}\) \(f(x)=\displaystyle\frac{5}{2}x^{-4}\)
The derivative is \(f'(x)=-10x^{-5}\)
\(\,\,\,\,\,f(x)=\frac{5}{2}x^{-4}\)
\(\,\,\,\,\,f'(x)=\frac{5}{2}(-4)x^{-5}\)
\(\,\,\,\,\,f'(x)=-10x^{-5}\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=-10x^{-5}\)
\(\textbf{18)}\) \(f(x)=3\sec x\)
The derivative is \(f'(x)=3\sec x\tan x\)
\(\,\,\,\,\,f(x)=3\sec x\)
\(\,\,\,\,\,\frac{d}{dx}(\sec x)=\sec x\tan x\)
\(\,\,\,\,\,f'(x)=3\sec x\tan x\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=3\sec x\tan x\)
\(\textbf{19)}\) \(f(x)=6\sqrt{x}\)
The derivative is \(f'(x)=\displaystyle\frac{3}{\sqrt{x}}\)
\(\,\,\,\,\,f(x)=6\sqrt{x}\)
\(\,\,\,\,\,f(x)=6x^{1/2}\)
\(\,\,\,\,\,f'(x)=6\left(\frac{1}{2}\right)x^{-1/2}\)
\(\,\,\,\,\,f'(x)=3x^{-1/2}\)
\(\,\,\,\,\,f'(x)=\displaystyle\frac{3}{\sqrt{x}}\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=\displaystyle\frac{3}{\sqrt{x}}\)
\(\textbf{20)}\) \(f(x)=-11x\)
The derivative is \(f'(x)=-11\)
\(\,\,\,\,\,f(x)=-11x\)
\(\,\,\,\,\,\frac{d}{dx}(x)=1\)
\(\,\,\,\,\,f'(x)=-11(1)\)
\(\,\,\,\,\,f'(x)=-11\)
\(\,\,\,\,\,\)The derivative is \(f'(x)=-11\)
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