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a: y=ln(x+1)

=>\(y'=\dfrac{1}{x+1}\)

=>\(y''=\dfrac{1'\left(x+1\right)-1\left(x+1\right)'}{\left(x+1\right)^2}=\dfrac{-1}{\left(x+1\right)^2}\)

b: y=tan 2x

=>\(y'=\dfrac{2}{cos^22x}\)

=>\(y''=\left(\dfrac{2}{cos^22x}\right)'=\dfrac{-2\cdot cos^22x'}{cos^42x}=\dfrac{-2\cdot2\cdot cos2x\left(cos2x\right)'}{cos^42x}\)

\(=\dfrac{4\cdot2\cdot sin2x}{cos^32x}=\dfrac{8\cdot sin2x}{cos^32x}\)

a: \(y=x\cdot e^{2x}\)

=>\(y'=\left(x\cdot e^{2x}\right)'\)

\(=x\cdot\left(e^{2x}\right)'+x'\cdot\left(e^{2x}\right)\)

\(=e^{2x}+2\cdot x\cdot e^{2x}\)

\(y''=\left(e^{2x}+2\cdot x\cdot e^{2x}\right)'\)

\(=\left(e^{2x}\right)'+\left(2\cdot x\cdot e^{2x}\right)'\)

\(=4\cdot e^{2x}+4\cdot x\cdot e^{2x}\)

b: \(y=ln\left(2x+3\right)\)

=>\(y'=\dfrac{\left(2x+3\right)'}{\left(2x+3\right)}=\dfrac{2}{2x+3}\)

=>\(y''=\left(\dfrac{2}{2x+3}\right)'=\dfrac{2\left(2x+3\right)'-2'\left(2x+3\right)}{\left(2x+3\right)^2}\)

\(=\dfrac{4}{\left(2x+3\right)^2}\)

HQ
Hà Quang Minh
Giáo viên
22 tháng 8 2023

\(a,y'=8x^3-9x^2+10x\\ \Rightarrow y''=24x^2-18x+10\\ b,y'=\dfrac{2}{\left(3-x\right)^2}\\ \Rightarrow y''=\dfrac{4}{\left(3-x\right)^3}\)

HQ
Hà Quang Minh
Giáo viên
22 tháng 8 2023

\(c,y'=2cos2xcosx-sin2xsinx\\ \Rightarrow y''=-5sin\left(2x\right)cos\left(x\right)-4cos\left(2x\right)sin\left(x\right)\\ d,y'=-2e^{-2x+3}\\ \Rightarrow y''=4e^{-2x+3}\)

a: \(y'=\left(x^2+2x\right)'\left(x^3-3x\right)+\left(x^2+2x\right)\left(x^3-3x\right)'\)

\(=\left(2x+2\right)\left(x^3-3x\right)+\left(x^2+2x\right)\left(3x^2-3\right)\)

\(=2x^4-6x^2+2x^3-6x+3x^4-3x^2+6x^3-6x\)

\(=5x^4+8x^3-9x^2-12x\)

b: y=1/-2x+5 

=>\(y'=\dfrac{2}{\left(2x+5\right)^2}\)

c: \(y'=\dfrac{\left(4x+5\right)'}{2\sqrt{4x+5}}=\dfrac{4}{2\sqrt{4x+5}}=\dfrac{2}{\sqrt{4x+5}}\)

d: \(y'=\left(sinx\right)'\cdot cosx+\left(sinx\right)\cdot\left(cosx\right)'\)

\(=cos^2x-sin^2x=cos2x\)

e: \(y=x\cdot e^x\)

=>\(y'=e^x+x\cdot e^x\)

f: \(y=ln^2x\)

=>\(y'=\dfrac{\left(-1\right)}{x^2}=-\dfrac{1}{x^2}\)

HQ
Hà Quang Minh
Giáo viên
22 tháng 9 2023

a) Đặt \(u = 3{\rm{x}}\) thì \(y = \sin u\). Ta có: \(u{'_x} = {\left( {3{\rm{x}}} \right)^\prime } = 3\) và \(y{'_u} = {\left( {\sin u} \right)^\prime } = \cos u\).

Suy ra \(y{'_x} = y{'_u}.u{'_x} = \cos u.3 = 3\cos 3{\rm{x}}\).

Vậy \(y' = 3\cos 3{\rm{x}}\).

b) Đặt \(u = \cos 2{\rm{x}}\) thì \(y = {u^3}\). Ta có: \(u{'_x} = {\left( {\cos 2{\rm{x}}} \right)^\prime } =  - 2\sin 2{\rm{x}}\) và \(y{'_u} = {\left( {{u^3}} \right)^\prime } = 3{u^2}\).

Suy ra \(y{'_x} = y{'_u}.u{'_x} = 3{u^2}.\left( { - 2\sin 2{\rm{x}}} \right) = 3{\left( {\cos 2{\rm{x}}} \right)^2}.\left( { - 2\sin 2{\rm{x}}} \right) =  - 6\sin 2{\rm{x}}{\cos ^2}2{\rm{x}}\).

Vậy \(y' =  - 6\sin 2{\rm{x}}{\cos ^2}2{\rm{x}}\).

c) Đặt \(u = \tan {\rm{x}}\) thì \(y = {u^2}\). Ta có: \(u{'_x} = {\left( {\tan {\rm{x}}} \right)^\prime } = \frac{1}{{{{\cos }^2}x}}\) và \(y{'_u} = {\left( {{u^2}} \right)^\prime } = 2u\).

Suy ra \(y{'_x} = y{'_u}.u{'_x} = 2u.\frac{1}{{{{\cos }^2}x}} = 2\tan x\left( {{{\tan }^2}x + 1} \right)\).

Vậy \(y' = 2\tan x\left( {{{\tan }^2}x + 1} \right)\).

d) Đặt \(u = 4 - {x^2}\) thì \(y = \cot u\). Ta có: \(u{'_x} = {\left( {4 - {x^2}} \right)^\prime } =  - 2{\rm{x}}\) và \(y{'_u} = {\left( {\cot u} \right)^\prime } =  - \frac{1}{{{{\sin }^2}u}}\).

Suy ra \(y{'_x} = y{'_u}.u{'_x} =  - \frac{1}{{{{\sin }^2}u}}.\left( { - 2{\rm{x}}} \right) = \frac{{2{\rm{x}}}}{{{{\sin }^2}\left( {4 - {x^2}} \right)}}\).

Vậy \(y' = \frac{{2{\rm{x}}}}{{{{\sin }^2}\left( {4 - {x^2}} \right)}}\).

HQ
Hà Quang Minh
Giáo viên
24 tháng 8 2023

\(a,y'=\left[\left(2x-3\right)^{10}\right]'\\ =10\left(2x-3\right)^9\left(2x-3\right)'\\ =20\left(2x-3\right)^9\\ b,y'=\left(\sqrt{1-x^2}\right)'\\ =\dfrac{\left(1-x^2\right)'}{2\sqrt{1-x^2}}\\ =-\dfrac{2x}{2\sqrt{1-x^2}}\\ =-\dfrac{x}{\sqrt{1-x^2}}\)

a: \(y'=\left[tan\left(e^x+1\right)\right]'=\dfrac{\left(e^x+1\right)'}{cos^2\left(e^x+1\right)}=\dfrac{e^x}{cos^2\left(e^x+1\right)}\)

b: \(y'=\left(\sqrt{sin3x}\right)'\)

\(=\dfrac{\left(sin3x\right)'}{2\sqrt{sin3x}}=\dfrac{3\cdot cos3x}{2\sqrt{sin3x}}\)

c: \(y=cot\left(1-2^x\right)\)

=>\(y'=\left[cot\left(1-2^x\right)\right]'\)

\(=\dfrac{-2}{sin^2\left(1-2^x\right)}\cdot\left(-2^x\cdot ln2\right)\)

\(=\dfrac{2^{x+1}\cdot ln2}{sin^2\left(1-2^x\right)}\)

HQ
Hà Quang Minh
Giáo viên
26 tháng 8 2023

\(a,y'=3x^2-4x+2\\ \Rightarrow y''=6x-4\\ b,y'=2xe^x+x^2e^x\\ \Rightarrow y''=4xe^x+x^2e^x+2e^x\)

17 tháng 8 2023

tham khảo:

a)\(y'\left(x\right)=5\left(\dfrac{2x-1}{x+2}\right)^4.\dfrac{\left(x+2\right)\left(2\right)-\left(2x-1\right).1}{\left(x+2\right)^2}\)

\(=\dfrac{10\left(2x-1\right)\left(x+2\right)^3}{\left(x+2\right)^4}=\dfrac{20x-50}{\left(x+2\right)^4}\)

b)\(y'\left(x\right)=\dfrac{2\left(x^2+1\right)-2x\left(2x\right)}{\left(x^2+1\right)^2}\)\(=\dfrac{2\left(1-x^2\right)}{\left(x^2+1\right)^2}\)

c)\(y'\left(x\right)=e^x.2sinxcosx+e^xsin^2x.2cosx\)

\(=2e^xsinx\left(cosx+sinxcosx\right)\)

\(=2e^xsinxcos^2x\)

d)\(y'\left(x\right)=\dfrac{1}{x\sqrt{x}}.\left(+\dfrac{1}{2\sqrt{x}}\right)\)

\(=\dfrac{1}{\sqrt{x}\left(2\sqrt{x}+\sqrt{x}+2\right)}\)

\(=\dfrac{1}{\sqrt{x}\left(3\sqrt{x}+2\right)}\)