easy differentiation-回答送分

2009-10-14 7:14 pm
Q1) y=ln e^x

Q2) y=(e^-x) ln x

Q3) y=e^(x^2 ln x^2)

Q4) y=ln e^(4x+1)

please find dy/dx, give a step and a answer, thanks a lot

回答 (1)

2009-10-14 7:20 pm
✔ 最佳答案
1. y = lnex

y = xlne (Property of logarithm)

y = x

dy/dx = dx/dx = 1


2. y = e-xlnx

dy/dx = e-x d(lnx)/dx + lnx d(e-x)/dx (Product rule)

dy/dx = e-x/x - e-xlnx

= e-x[(1/x) - lnx]

3. y = exp(x2lnx2)

dy/dx = d(exp(x2lnx2))/d(x2lnx2) d(x2lnx2)/dx (Chain rule)

= exp(x2lnx2) ((2x)x2 / x2) X 2xlnx2

= 4x2(lnx2)exp(x2lnx2)

4. y = lne4x+1

y = 4x + 1

dy/dx = d(4x + 1)/dx = 4
參考: Physics king


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