CAT Exam  >  CAT Questions  >   Let f(x) = max (5x, 52 - 2x2), where x is an... Start Learning for Free
Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)
Correct answer is '20'. Can you explain this answer?
Verified Answer
Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. T...
The minimum value of the function will occur when the expressions inside the function are equal.
So, 5x = 52 - 2x2or, 2x2 + 5x - 52 = 0
on solving, we get x = 4 or 13/-2
But, it is given that x is a positive number.
So, x = 4
and the minimum value = 5*4 = 20
Hence, 20 is the correct answer.
View all questions of this test
Most Upvoted Answer
Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. T...
Understood. Here is the detailed explanation of the answer:

Given Function:
The given function is f(x) = max(5x, 52 - 2x^2), where x is any positive real number.

Finding the Minimum Possible Value of f(x):
To find the minimum possible value of f(x), we need to analyze the two cases:
1. When 5x is the maximum value.
2. When 52 - 2x^2 is the maximum value.

Case 1: When 5x is the Maximum Value
When 5x is the maximum value, it means that 5x is greater than or equal to 52 - 2x^2. We can set up the following inequality:
5x ≥ 52 - 2x^2

Solving the Inequality:
To solve the inequality, we can rearrange it:
2x^2 + 5x - 52 ≤ 0

We can factorize the quadratic equation:
(2x - 13)(x + 4) ≤ 0

The roots of the equation are x = 13/2 and x = -4.
Since x is a positive real number, we can discard the negative root.
So, the range of x is x ≤ 13/2.

Case 2: When 52 - 2x^2 is the Maximum Value
When 52 - 2x^2 is the maximum value, it means that 52 - 2x^2 is greater than or equal to 5x. We can set up the following inequality:
52 - 2x^2 ≥ 5x

Solving the Inequality:
To solve the inequality, we can rearrange it:
2x^2 + 5x - 52 ≥ 0

We can factorize the quadratic equation:
(2x - 13)(x + 4) ≥ 0

The roots of the equation are x = 13/2 and x = -4.
Since x is a positive real number, we can discard the negative root.
So, the range of x is x ≥ 13/2.

Combining the Ranges:
From both cases, we have the range of x as x ≤ 13/2 and x ≥ 13/2.
Since the range is restricted to x = 13/2, we can conclude that the minimum possible value of f(x) is achieved when x = 13/2.

Calculating f(x) at x = 13/2:
Substituting x = 13/2 into the given function,
f(13/2) = max(5 * 13/2, 52 - 2 * (13/2)^2)
= max(65/2, 52 - 2 * (169/4))
= max(65/2, 52 - 338/4)
= max(65/2, 52 - 169/2)
= max(65/2, -117/2)
= 65/2

Therefore, the minimum possible value of f(x) is 65/2, which is equal to 32.5.

Conclusion:
The correct answer is
Attention CAT Students!
To make sure you are not studying endlessly, EduRev has designed CAT study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in CAT.
Explore Courses for CAT exam
Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)Correct answer is '20'. Can you explain this answer?
Question Description
Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)Correct answer is '20'. Can you explain this answer? for CAT 2024 is part of CAT preparation. The Question and answers have been prepared according to the CAT exam syllabus. Information about Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)Correct answer is '20'. Can you explain this answer? covers all topics & solutions for CAT 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)Correct answer is '20'. Can you explain this answer?.
Solutions for Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)Correct answer is '20'. Can you explain this answer? in English & in Hindi are available as part of our courses for CAT. Download more important topics, notes, lectures and mock test series for CAT Exam by signing up for free.
Here you can find the meaning of Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)Correct answer is '20'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)Correct answer is '20'. Can you explain this answer?, a detailed solution for Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)Correct answer is '20'. Can you explain this answer? has been provided alongside types of Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)Correct answer is '20'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice Let f(x) = max (5x, 52 - 2x2), where x is any positive real number. Then the minimum possible value of f(x)Correct answer is '20'. Can you explain this answer? tests, examples and also practice CAT tests.
Explore Courses for CAT exam

Top Courses for CAT

Explore Courses
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev