A) Is bounded
B) Has a local maxima
C) Has a local minima
D) Is strictly increasing
Correct Answer: D
Solution :
Given \[f(x)={{x}^{3}}+b{{x}^{2}}+cx+d\] \ \[f'(x)=3{{x}^{2}}+2bx+c\] Now its discriminant \[=4({{b}^{2}}-3c)\] Þ \[4({{b}^{2}}-c)-8c<0,\] as \[{{b}^{2}}<c\] and \[c>0\] Therefore, \[f'(x)>0\]for all \[x\in R\] Hence f is strictly increasing.You need to login to perform this action.
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