Derivative Formula:
Actual derivative formula:
If y = f(x), then
\(\LARGE f’(x)=\lim_{\triangle x \rightarrow 0}\frac{f(x+ \triangle x)-f(x)}{\triangle x}\)
Basic Derivative formula:
- \(\frac{d}{dx}\)(c) = 0, where c is constant.
- \(\frac{d}{dx}\)(x) = 1
- \(\frac{d}{dx}\)(xn) = n xn-1
- \(\frac{d}{dx}\)[f(x)]n = n [f(x)]n-1 \(\frac{d}{dx}\) f(x)
- \(\frac{d}{{dx}}\sqrt x= \frac{1}{{2\sqrt x }}\)
- \(\frac{d}{dx}\) C∙f(x) = C ∙ \(\frac{d}{dx}\) f(x) = C∙f’(x)
- \(\frac{d}{{dx}}[f(x) \pm g(x)] = \frac{d}{{dx}}f(x) \pm \frac{d}{{dx}}g(x) = f'(x) \pm g'(x)\)
- \(\frac{d}{dx}\) [f(x) ∙ g(x)] = f(x) \(\frac{d}{dx}\) g(x) + g(x) \(\frac{d}{dx}\) f(x)
This is called product rule of derivative.
- \(\frac{d}{{dx}}[\frac{{f(x)}}{{g(x)}}] = \frac{{g(x)\frac{d}{{dx}}f(x) - f(x)\frac{d}{{dx}}g(x)}}{{{{[g(x)]}^2}}}\)
This is quotient rule of derivative.
Chain Rule:
- [f(g(x))]’= f’(g(x))g’(x)
- \(\frac{du}{dx}\) = \(\frac{du}{dv}\)∙\(\frac{dv}{dx}\)
- \(\large \frac{du}{dx}=\frac{\frac{du}{dv}}{\frac{dx}{dv}}\)
- \(\large \frac{dy}{dx}=\frac{1}{\frac{dx}{dy}}\)
Logarithm Derivative Formula:
- \(\frac{d}{dx}\)ln x = \(\frac{1}{x}\)
- \(\frac{d}{dx}\)logax = \(\frac{1}{x\:ln\:a}\)
- \(\frac{d}{{dx}}\ln f(x) = \frac{1}{{f(x)}}\frac{d}{{dx}}f(x)\)
- \(\frac{d}{{dx}}{\log _a}f(x) = \frac{1}{{f(x)\ln a}}\frac{d}{{dx}}f(x)\)
Derivative formula for exponential functions:
- \(\frac{d}{dx}\)ex = ex
- \(\frac{d}{{dx}}{a^x} = {a^x}\ln a\)
- \(\frac{d}{dx}\)ef(x) = ef(x) f’(x)
- \(\frac{d}{dx}\) af(x) = af(x)ln a f’(x)
- \(\frac{d}{dx}\) xx = xx(1 + ln x)
Derivative Formula for Trigonometric Formula:
- \(\frac{d}{dx}\) sin x = cos x
- \(\frac{d}{dx}\) cos x = - sinx
- \(\frac{d}{dx}\) tan x = sec2 x
- \(\frac{d}{dx}\) cot x = - cosec2x
- \(\frac{d}{dx}\) sec x = sec x∙tan x
- \(\frac{d}{dx}\) cosec x = - cosec x∙cot x
Derivative formula for Inverse Trigonometric functions:
- \(\frac{d}{{dx}}si{n^{ - 1}}x = \frac{1}{{\sqrt {1 - {x^2}} }},{\text{ }} - 1 < x < 1\)
- \(\frac{d}{{dx}}co{s^{ - 1}}x = \frac{{ - 1}}{{\sqrt {1 - {x^2}} }},{\text{ }} - 1 < x < 1\)
- \(\frac{d}{{dx}}ta{n^{ - 1}}x = \frac{1}{{1 + {x^2}}}\)
- \(\frac{d}{{dx}}co{t^{ - 1}}x = \frac{{ - 1}}{{1 + {x^2}}}\)
- \(\frac{d}{{dx}}se{c^{ - 1}}x = \frac{1}{{x\sqrt {{x^2} - 1} }},{\text{ }}\left| x \right| > 1\)
- \(\frac{d}{{dx}}co{\sec ^{ - 1}}x = \frac{{ - 1}}{{x\sqrt {{x^2} - 1} }},{\text{ }}\left| x \right| > 1\)
Derivative formula for hyperbolic functions:
- \(\frac{d}{dx}\) sinh x = cosh x
- \(\frac{d}{dx}\) cosh x = sinh x
- \(\frac{d}{dx}\) tanh x = sech2x
- \(\frac{d}{dx}\) coth x = - cosech2x
- \(\frac{d}{dx}\) sech x = -sech x∙tanh x
- \(\frac{d}{dx}\) cosech x = - cosech x∙coth x
Derivative formula for Inverse Hyperbolic functions:
- \(\frac{d}{{dx}}Sin{h^{ - 1}}x = \frac{1}{{\sqrt {1 + {x^2}} }}\)
- \(\frac{d}{{dx}}Cos{h^{ - 1}}x = \frac{1}{{\sqrt {{x^2} - 1} }}\)
- \(\frac{d}{{dx}}Tan{h^{ - 1}}x = \frac{1}{{1 - {x^2}}},{\text{ }}\left| x \right| < 1\)
- \(\frac{d}{{dx}}Cot{h^{ - 1}}x = \frac{1}{{{x^2} - 1}},{\text{ }}\left| x \right| > 1\)
- \(\frac{d}{{dx}}Sec{h^{ - 1}}x = \frac{{ - 1}}{{x\sqrt {1 - {x^2}} }},{\text{ }}0 < x < 1\)
- \(\frac{d}{{dx}}Co\sec {h^{ - 1}}x = \frac{{ - 1}}{{x\sqrt {1 + {x^2}} }},{\text{ }}x > 0\)
Derivative formula examples:
- Find the derivative of the function given by f(x) = sin (x)2.
Solution:
f(x) = sin(x2)
f’(x) = \(\frac{d}{dx}\)( sin x2) x \(\frac{d}{dx}\) x2
= (cos x2) (2x)
= 2x cos x2
- Find \(\frac{dy}{dx}\) if x – y = π.
Solution:
We can write the equation as
y = x – π
\(\frac{dy}{dx}\) = 1
- Find \(\frac{dy}{dx}\), if y + sin y = cos x.
Solution:
We differentiate the relationship directly with respect to x,
\(\frac{dy}{dx}\) + \(\frac{d}{dx}\)(sin y) = \(\frac{d}{dx}\)(cos x)
which implies using chain rule
\(\frac{dy}{dx}\) + cos y \(\frac{dy}{dx}\) = -sin x
This allows \(\frac{dy}{dx}\) = - \(\frac{sin x}{1 + cos y}\)
where y ≠ (2n + 1) π