If the function has a horizontal tangent and a point of inflection for the same value of

MATHEMATICS · Single correct · CBSE · Mathematics · Applications of Derivatives · Applications of Derivatives

Problem

If the function

f(x)=x^4+bx^2+8x

has a horizontal tangent and a point of inflection for the same value of

x

, then the value of

b

is equal to (1) -1 (2) 1 (3) 6 (4) -6