1.e^(x+3)=(e^x)+3 求x2.求x最大值log5(x^2)-log5(x+2)=33.简化tan(2cos^-1(x/5))

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1.e^(x+3)=(e^x)+3 求x2.求x最大值log5(x^2)-log5(x+2)=33.简化tan(2cos^-1(x/5))
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1.e^(x+3)=(e^x)+3 求x2.求x最大值log5(x^2)-log5(x+2)=33.简化tan(2cos^-1(x/5))
1.e^(x+3)=(e^x)+3 求x
2.求x最大值
log5(x^2)-log5(x+2)=3
3.简化
tan(2cos^-1(x/5))


1.e^(x+3)=(e^x)+3 求x2.求x最大值log5(x^2)-log5(x+2)=33.简化tan(2cos^-1(x/5))
1
原式可化为:
e^3*e^x-e^x=3
(e^3-1)e^x=3
e^x=3/(e^3-1)
x=ln[3/(e^3-1)]=ln3-ln(e^3-1)
2
定义域为:
{x^2>0
{x+2>0
D=(-2,0)∪(0+∞)
原式可化为:
log5[x^2/(x+2)]=3
x^2/(x+2)=5^3=125
x^2-(5^3)x-2*(5^3)=0
Δ=(5^3)^2+8(5^3)=5^2*(665)
x=[125+5√665]/2
3
设α=arccos(x/5)
cosα=x/5
sinα=√1-cos^2(α)=√(25-x^2)/5
sin2α=2sinαcosα=2x√(25-x^2)/25
cos2α=2(x/5)^2-1=(2x^2-25)/25
原式=tan2α=sin2α/cos2α=2x√(25-x^2)/(2x^2-25)

1.e^x * e^3-e^x=3
e^x (e^3-1)=3
e^x =3/(e^3-1)
x=ln 3-ln(e^3-1)
2.log5(x^2)/(x+2)=log5 125
(x^2)/(x+2)=125
x^2=125(x+2)
x^2-125x+250=0
再利用一元二次方程求根公式解出

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