A) It is decreasing everywhere
B) It is decreasing only In \[\left( 0,\infty \right)\]
C) It is increasing every where
D) It is increasing only in \[\left( -\infty ,0 \right)\]
Correct Answer: C
Solution :
[c] \[f'\left( x \right)=5{{x}^{4}}-60{{x}^{2}}+240\] \[=5\left( {{x}^{4}}-12{{x}^{2}}+48 \right)\text{ }=\text{ }5\left[ {{\left( {{x}^{2}}-6 \right)}^{2}}+12 \right]\] \[\Rightarrow f'\left( x \right)>O\forall x\in R\] i.e., f(x) is increasing everywhere
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