Question

Consider, $f(x)=\left({\lambda }^4-2{\lambda }^2\right)x+3\cos x,\lambda \in R$.
The least positive integral value of $\lambda$ for which $f(x)$ is monotonically increasing for all $x\in R$.

• A. 2
• B. 3
• C. 4
• D. 5

Answer 1

Answer: (A)

Correct answer is (a) 2