CAT Quantitative Ability Questions | CAT Functions questions
CAT/2004
Question . 31
Let f (x) = ax² – b | x |, where a and b are constants. Then at x = 0, f (x) is
A : maximized whenever a > 0, b > 0B : maximized whenever a > 0, b < 0C : minimized whenever a > 0, b > 0D : minimized whenever a > 0, b < 0
View Answer Explanatory Answer
Method of solving this CAT Quantitative Ability Question from Functions question
(d) f (x) = ax² – bx. In this function, x² and x are always positive.
The value thus depends on a and b. f (0) = a – b. Using different options, we find that a – b will be positive if a > 0 and b < 0.
The minimum value of a positive function is 0. Hence (d) is correct option.