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f(x)=xlnx+x,forwhatvalueofxisthetangentlinetothegraphoffat(x,f(x))horizontal?为什么答案是e^-2.

题目详情
f(x)=xlnx+x,
for what value of x is the tangent line to the graph of f at (x,f(x)) horizontal?为什么答案是e^-2.
▼优质解答
答案和解析
Differentiate f(x)
lnx+1+1=0
lnx=-2
x=e^(-2)
because horizontal ,so this tangent line is paralleled to x-axis.