Tìm đạo hàm của hàm số y = ( x 2 - x + 3 ) 3 4 .
A. y ' = 3 2 x - 1 4 x 2 - x + 3 4
B. y ' = 3 2 x - 1 2 x 2 - x + 3 4
C. y ' = 3 4 x 2 - x + 3 4
D. y ' = 3 2 x 2 - x + 3 4
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\(a,y'=\left(x^3-4x^2+5\right)'=3x^2-8x\\ b,y''=\left(3x^2-8x\right)'=6x-8\)
1) \(f\left(x\right)=2x-5\)
\(f'\left(x\right)=2\)
\(\Rightarrow f'\left(4\right)=2\)
2) \(y=x^2-3\sqrt[]{x}+\dfrac{1}{x}\)
\(\Rightarrow y'=2x-\dfrac{3}{2\sqrt[]{x}}-\dfrac{1}{x^2}\)
3) \(f\left(x\right)=\dfrac{x+9}{x+3}+4\sqrt[]{x}\)
\(\Rightarrow f'\left(x\right)=\dfrac{1.\left(x+3\right)-1.\left(x+9\right)}{\left(x-3\right)^2}+\dfrac{4}{2\sqrt[]{x}}\)
\(\Rightarrow f'\left(x\right)=\dfrac{x+3-x-9}{\left(x-3\right)^2}+\dfrac{2}{\sqrt[]{x}}\)
\(\Rightarrow f'\left(x\right)=\dfrac{12}{\left(x-3\right)^2}+\dfrac{2}{\sqrt[]{x}}\)
\(\Rightarrow f'\left(x\right)=2\left[\dfrac{6}{\left(x-3\right)^2}+\dfrac{1}{\sqrt[]{x}}\right]\)
\(\Rightarrow f'\left(1\right)=2\left[\dfrac{6}{\left(1-3\right)^2}+\dfrac{1}{\sqrt[]{1}}\right]=2\left(\dfrac{3}{2}+1\right)=2.\dfrac{5}{2}=5\)
1. \(y'=3x^2\sqrt{x}+\dfrac{x^3-5}{2\sqrt{x}}=\dfrac{7x^3-5}{2\sqrt{x}}\)
2. \(y'=3x^5+\dfrac{3}{x^2}+\dfrac{1}{\sqrt{x}}\)
3. \(y'=2-\dfrac{2}{\left(x-2\right)^2}\)
1) \(y=x^2-3\sqrt[]{x}+\dfrac{1}{x}\)
\(\Rightarrow y=2x-\dfrac{3}{2\sqrt[]{x}}-\dfrac{1}{x^2}\)
2) \(f\left(x\right)=\dfrac{x+9}{x+3}+4\sqrt[]{x}\)
\(\Rightarrow f'\left(x\right)=\dfrac{1.\left(x+3\right)-1\left(x+9\right)}{\left(x+3\right)^2}+\dfrac{2}{\sqrt[]{x}}\)
\(\Rightarrow f'\left(x\right)=\dfrac{x+3-x-9}{\left(x+3\right)^2}+\dfrac{2}{\sqrt[]{x}}\)
\(\Rightarrow f'\left(x\right)=\dfrac{-6}{\left(x+3\right)^2}+\dfrac{2}{\sqrt[]{x}}\)
\(\Rightarrow f'\left(1\right)=\dfrac{-6}{\left(1+3\right)^2}+\dfrac{2}{\sqrt[]{1}}=-\dfrac{3}{8}+2=\dfrac{13}{8}\)
a: \(y'=4\cdot3x^2-3\cdot2x+2=12x^2-6x+2\)
b: \(y'=\dfrac{\left(x+1\right)'\left(x-1\right)-\left(x+1\right)\left(x-1\right)'}{\left(x-1\right)^2}=\dfrac{x-1-x-1}{\left(x-1\right)^2}=\dfrac{-2}{\left(x-1\right)^2}\)
c: \(y'=-2\cdot\left(\sqrt{x}\cdot x\right)'\)
\(=-2\cdot\left(\dfrac{x+x}{2\sqrt{x}}\right)=-2\cdot\dfrac{2x}{2\sqrt{x}}=-2\sqrt{x}\)
d: \(y'=\left(3sinx+4cosx-tanx\right)\)'
\(=3cosx-4sinx+\dfrac{1}{cos^2x}\)
e: \(y'=\left(4^x+2e^x\right)'\)
\(=4^x\cdot ln4+2\cdot e^x\)
f: \(y'=\left(x\cdot lnx\right)'=lnx+1\)
Tính đạo hàm của các hàm số sau:
a) \(y = {x^3} - 3{x^2} + 2x + 1;\)
b) \(y = {x^2} - 4\sqrt x + 3.\)
tham khảo:
a)\(y'=\dfrac{d}{dx}\left(x^3\right)-\dfrac{d}{dx}\left(3x^2\right)+\dfrac{d}{dx}\left(2x\right)+\dfrac{d}{dx}\left(1\right)\)
\(y'=3x^2-6x+2\)
b)\(\dfrac{d}{dx}\left(x^n\right)=nx^{n-1}\)
\(\dfrac{d}{dx}\left(\sqrt{x}\right)=\dfrac{1}{2\sqrt{x}}\)
\(\dfrac{d}{dx}\left(f\left(x\right)+g\left(x\right)\right)=f'\left(x\right)+g'\left(x\right)\)
\(\dfrac{d}{dx}\left(cf\left(x\right)\right)=cf'\left(x\right)\)
\(y'=\dfrac{d}{dx}\left(x^2\right)-\dfrac{d}{dx}\left(4\sqrt{x}\right)+\dfrac{d}{dx}\left(3\right)\)
\(y'=2x-2\sqrt{x}\)
a) Với bất kì \({x_0} \in \mathbb{R}\), ta có:
\(f'\left( {{x_0}} \right) = \mathop {\lim }\limits_{x \to {x_0}} \frac{{f\left( x \right) - f\left( {{x_0}} \right)}}{{x - {x_0}}} = \mathop {\lim }\limits_{x \to {x_0}} \frac{{x - {x_0}}}{{x - {x_0}}} = \mathop {\lim }\limits_{x \to {x_0}} 1 = 1\)
Vậy \(f'\left( x \right) = {\left( x \right)^\prime } = 1\) trên \(\mathbb{R}\).
b) Ta có:
\(\begin{array}{l}{\left( {{x^2}} \right)^\prime } = 2{\rm{x}}\\{\left( {{x^3}} \right)^\prime } = 3{{\rm{x}}^2}\\...\\{\left( {{x^n}} \right)^\prime } = n{{\rm{x}}^{n - 1}}\end{array}\)
1.
\(y'=\left(\dfrac{x}{lnx}\right)'.3^{\dfrac{x}{lnx}}.ln3=\dfrac{lnx-1}{ln^2x}.3^{\dfrac{x}{lnx}}.ln3\)
2.
\(y'=\left(tanx\right)'.tanx+\left(tanx\right)'.\dfrac{1}{tanx}=\dfrac{tanx}{cos^2x}+\dfrac{1}{tanx.cos^2x}\)
3.
\(y=\left(ln2x\right)^{\dfrac{2}{3}}\Rightarrow y'=\left(ln2x\right)'.\dfrac{2}{3}.\left(ln2x\right)^{-\dfrac{1}{3}}=\dfrac{1}{3x\sqrt[3]{ln2x}}\)
a, \(y=3x^4-7x^3+3x^2+1\)
\(y'=12x^3-21x^2+6x\)
b, \(y=\left(x^2-x\right)^3\)
\(y'=3\left(x^2-x\right)^2\left(2x-1\right)\)
c, \(y=\dfrac{4x-1}{2x+1}\)
\(y'=\dfrac{4+2}{\left(2x+1\right)^2}\)
\(y'=\dfrac{6}{\left(2x+1\right)^2}\)
a: y=3x^4-7x^3+3x^2+1
=>y'=3*4x^3-7*3x^2+3*2x
=12x^3-21x^2+6x
b: \(y'=\left[\left(x^2-x\right)^3\right]'\)
\(=3\left(2x-1\right)\left(x^2-x\right)^2\)
c: \(y'=\dfrac{\left(4x-1\right)'\left(2x+1\right)-\left(4x-1\right)\left(2x+1\right)'}{\left(2x+1\right)^2}\)
\(=\dfrac{4\left(2x+1\right)-2\left(4x-1\right)}{\left(2x+1\right)^2}=\dfrac{6}{\left(2x+1\right)^2}\)
Chọn A
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