CAT 2018 Question Paper | Quants Slot 2
CAT Previous Year Paper | CAT Functions Questions | Question 30
CAT Questions In CAT 2018 Question Paper, we witnessed some beautiful questions that lay great emphasis on the fundas . This question from Functions is one such question where in you need to compute the maximum possible value of a function. If you feel your fundas are not great, do not worry: 2IIM offers some wonderful online courses that would aid in grasping the basic concepts and help you solve problems in a well-structured manner. To know about the courses, visit: 2IIM's Online CAT Coaching
Question 30 : Let f(x)= max{5x, 52 - 2x2}, where x is any positive real number.Then the minimum possible value of f(x) is [TITA]
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Explanatory Answer
Method of solving this CAT Question from Functions
Given that f(x) = max{5x , 52 - 2x2}, where x is any positive real number.
The minimum possible value of f(x) has to found.
The minimum possible value is obtained if the two curves intersect or
5x = 52 - 2x2
2x2 + 5x – 52 = 0
2x2 – 8x + 13x – 52 = 0
2x(x - 4) + 13(x - 4) = 0
(2x + 13)(x - 4) = 0
x = \\frac{-13}{2}) or 4
One of these would be the minimum possible value
It is given that x is a positive real number. So, we have to consider only when x = 4
When x = 4
5x = 5 × 4 = 20
52 - 2x2 = 52 – 2(4)2 = 20
The minimum possible value of f(x) is 20
The question is "Let f(x)= max{5x, 52 - 2x2}, where x is any positive real number.Then the minimum possible value of f(x) is [TITA]"
Hence, the answer is 20
