GATE Electrical 2020 | Question: 26

Question

For real numbers, $\text{x}$ and $\text{y}$, with $y=3x^{2}+3x+1$, the maximum and minimum value of $\text{y}$ for $\text{x}$ $\in \left [ -2,0 \right ]$ are respectively, ______.

• A. $7$ and $1/4$
• B. $7$ and $1$
• C. $-2$ and $-1/2$
• D. $1$ and $1/4$

Answer 1

Ans : option A

Concept : Find extrema of a continuous differentiable function on a closed interval by:

• compute derivative and find critical points inside interval,

• evaluate the function at critical points and at endpoints, then pick largest and smallest values.