Question

Let y = f (x) be a cubic polynomial function which attain its local maximum at x = 3 and point of inflection is at x = 7, then

• A. Local minimum is at x = 11
• B. Local minimum is at x = $\sqrt{21}$
• C. Local minimum is at x = –1
• D. Data insufficient

Answer 1

Answer: (A)

Local minimum is at x = 11

Answer 2

Let the local minimum be at x = a.

Then $\frac{a + 3}{2}$= 7

i.e. a = 11