Math assignment 9

Name: Rain Xia       Student Number: 59118159

Use the function, derivative and second derivative to sketch the graph of f(x) =x^x

f(x)=x^x     domain: x≥0.      intercepts: when x=0, y=1, therefore the intercept is (0,1).                                asymptotes: lim x->∞f(x)=∞      lim x->0 f(x)=1

f'(x)=(x^x)(1+lnx)     intervals of increase and decrease: when (x^x)(1+lnx)<0.368, the function decreases, when (x^x)(1+lnx)>0.368, the function increases.     extrema: f'(x)=(x^x)(1+lnx)=0 when x=0.368, therefore the extrema for f(x) is x=0.368 and it is the global minimum of the funtion.

f”(x)=x^x*[(lnx+1)²+1/x]     intervals of concavity: x^x*[(lnx+1)²+1/x]≥0, therefore f(x) is concave up.     inflection points: (0.368,0.692)

Based on these points and information, we can draw the diagram of function f(x)=x^x.QQ图片20151119214337

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