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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: \(y=ln^2x\)
=>\(y'=\dfrac{\left(-1\right)}{x^2}=-\dfrac{1}{x^2}\)
a) Cách 1: y' = (9 -2x)'(2x3- 9x2 +1) +(9 -2x)(2x3- 9x2 +1)' = -2(2x3- 9x2 +1) +(9 -2x)(6x2 -18x) = -16x3 +108x2 -162x -2.
Cách 2: y = -4x4 +36x3 -81x2 -2x +9, do đó
y' = -16x3 +108x2 -162x -2.
b) y' = .(7x -3) +(7x -3)'= (7x -3) +7.
c) y' = (x -2)'√(x2 +1) + (x -2)(√x2 +1)' = √(x2 +1) + (x -2) = √(x2 +1) + (x -2) = √(x2 +1) + = .
d) y' = 2tanx.(tanx)' - (x2)' = .
e) y' = sin = sin.
xét hàm số y=ln(\(x+\sqrt{1+x^2}\))
Ta có
y'=\(\frac{1}{x+\sqrt{1+x^2}}\left(1+\frac{x}{\sqrt{1+x^2}}\right)=\frac{1}{x+\sqrt{1+x^2}}.\frac{x+\sqrt{1+x^2}}{\sqrt{1+x^2}}=\frac{1}{\sqrt{1+x^2}}\)
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: \(y=ln\left(2x+3\right)\)
=>\(y'=\dfrac{\left(2x+3\right)'}{\left(2x+3\right)}=\dfrac{2}{2x+3}\)
=>\(y''=\left(\dfrac{2}{2x+3}\right)'=\dfrac{2\left(2x+3\right)'-2'\left(2x+3\right)}{\left(2x+3\right)^2}\)
\(=\dfrac{4}{\left(2x+3\right)^2}\)
Y'=\(\frac{1}{e^x+\sqrt{1+e^{2x}}}\left(e^x+\frac{2e^{2x}}{2\sqrt{1+e^{2x}}}\right)=\frac{1}{e^x+\sqrt{1+e^{2x}}}.\frac{e^x\left(\sqrt{1+e^{2x}}+e^x\right)}{\sqrt{1+e^{2x}}}=\frac{e^x}{\sqrt{1+e^{2x}}}\)