Find the best tutors and institutes for Class 12 Tuition
Q28:
For all real values of $x$, the minimum value of $\frac{1-x+x^2}{1+x+x^2}$ is
Solution :
Step 1: Functional Representation and Objective
Let the given function be denoted as $f(x)$:
$f(x) = \frac{1-x+x^2}{1+x+x^2}$
Our objective is to find the minimum value of $f(x)$ for all $x \in \mathbb{R}$. [By the Method of Derivatives for optimization]
Step 2: Differentiation with respect to $x$
We apply the Quotient Rule, $\frac{d}{dx} \left[ \frac{u}{v} \right] = \frac{u'v - uv'}{v^2}$, where $u = 1-x+x^2$ and $v = 1+x+x^2$.
$u' = 2x - 1$
$v' = 2x + 1$
$f'(x) = \frac{(2x-1)(1+x+x^2) - (1-x+x^2)(2x+1)}{(1+x+x^2)^2}$
Step 3: Algebraic Simplification of the Numerator
Expanding the numerator terms:
Numerator $= (2x + 2x^2 + 2x^3 - 1 - x - x^2) - (2x + 1 - 2x^2 - x + 2x^3 + x^2)$
Numerator $= (2x^3 + x^2 + x - 1) - (2x^3 - x^2 + x + 1)$
Numerator $= 2x^3 + x^2 + x - 1 - 2x^3 + x^2 - x - 1$
Numerator $= 2x^2 - 2$
$f'(x) = \frac{2(x^2 - 1)}{(1+x+x^2)^2}$
Step 4: Locating Critical Points
Set $f'(x) = 0$ to find stationary points:
$2(x^2 - 1) = 0 \implies x^2 = 1 \implies x = \pm 1$
Critical points are $x = 1$ and $x = -1$.
Step 5: Evaluating Function Values at Critical Points
Evaluate $f(x)$ at $x = 1$ and $x = -1$ to determine the local extrema:
- For $x = 1$: $f(1) = \frac{1 - 1 + 1^2}{1 + 1 + 1^2} = \frac{1}{3}$
- For $x = -1$: $f(-1) = \frac{1 - (-1) + (-1)^2}{1 + (-1) + (-1)^2} = \frac{1 + 1 + 1}{1 - 1 + 1} = \frac{3}{1} = 3$
Step 6: Analysis of Global Behavior
Since the denominator $(1+x+x^2)$ is always positive (discriminant $D = 1-4 = -3 < 0$), and considering the limits as $x \to \pm \infty$:
$\lim_{x \to \infty} f(x) = 1$ and $\lim_{x \to -\infty} f(x) = 1$.
By comparing the values $1/3$, $3$, and $1$, the minimum value is identified as $1/3$.
Final Solution: The minimum value of the function is \frac{1}{3}.
More Questions from Class 12 Mathematics Application of Derivatives EXERCISE 6.3
- Q1(i): Find the maximum and minimum values, if any, of the following functions given by (i) $f(x) = (2x – 1)^2 + 3$
- Q1(ii): Find the maximum and minimum values, if any, of the following functions given by (ii) $f(x) = 9x^2 + 12x + 2$
- Q1(iii): Find the maximum and minimum values, if any, of the following functions given by (iii) $f(x) = – (x – 1)^2 + 10$
- Q1(iv): Find the maximum and minimum values, if any, of the following functions given by (iv) $g(x) = x^3 + 1$
- Q2(i): Find the maximum and minimum values, if any, of the following functions given by (i) $f(x) = | x + 2 | – 1$
- Q2(ii): Find the maximum and minimum values, if any, of the following functions given by (ii) $g(x) = – | x + 1| + 3$
- Q2(iii): Find the maximum and minimum values, if any, of the following functions given by (iii) $h(x) = \sin(2x) + 5$
- Q2(iv): Find the maximum and minimum values, if any, of the following functions given by (iv) $f(x) = | \sin 4x + 3|$
- Q2(v): Find the maximum and minimum values, if any, of the following functions given by (v) $h(x) = x + 1, x \in (– 1, 1)$
- Q3(i): Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be: (i) $f(x) = x^2$
- Q3(ii): Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be: (ii) $g(x) = x^3 – 3x$
- Q3(iii): Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be: (iii) $h(x) = \sin x + \cos x, 0 < x < \frac{\pi}{2}$
- Q3(iv): Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be: (iv) $f(x) = \sin x – \cos x, 0 < x < 2\pi$
- Q3(v): Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be: (v) $f(x) = x^3 – 6x^2 + 9x + 15$
- Q3(vi): Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be: (vi) $g(x) = \frac{x}{2} + \frac{2}{x}, x > 0$
- Q3(vii): Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be: (vii) $g(x) = \frac{1}{x^2 + 2}$
- Q3(viii): Find the local maxima and local minima, if any, of the following functions. Find also the local maximum and the local minimum values, as the case may be: (viii) $f(x) = x \sqrt{1-x}, 0 < x < 1$
- Q4(i): Prove that the following functions do not have maxima or minima: (i) $f(x) = e^x$
- Q4(ii): Prove that the following functions do not have maxima or minima: (ii) $g(x) = \log x$
- Q4(iii): Prove that the following functions do not have maxima or minima: (iii) $h(x) = x^3 + x^2 + x +1$
- Q5(i): Find the absolute maximum value and the absolute minimum value of the following functions in the given intervals: (i) $f(x) = x^3, x \in [– 2, 2]$
- Q5(ii): Find the absolute maximum value and the absolute minimum value of the following functions in the given intervals: (ii) $f(x) = \sin x + \cos x, x \in [0, \pi]$
- Q5(iii): Find the absolute maximum value and the absolute minimum value of the following functions in the given intervals: (iii) $f(x) = 4x - \frac{1}{2}x^2, x \in [-2, \frac{9}{2}]$
- Q5(iv): Find the absolute maximum value and the absolute minimum value of the following functions in the given intervals: (iv) $f(x) = (x-1)^2 + 3, x \in [-3, 1]$
- Q6: Find the maximum profit that a company can make, if the profit function is given by $p(x) = 41 – 72x – 18x^2$
- Q7: Find both the maximum value and the minimum value of $3x^4 – 8x^3 + 12x^2 – 48x + 25$ on the interval $[0, 3]$.
- Q8: At what points in the interval $[0, 2\pi]$, does the function $\sin 2x$ attain its maximum value?
- Q9: What is the maximum value of the function $\sin x + \cos x$?
- Q10: Find the maximum value of $2x^3 – 24x + 107$ in the interval $[1, 3]$. Find the maximum value of the same function in $[–3, –1]$.
- Q11: It is given that at $x = 1$, the function $x^4 – 62x^2 + ax + 9$ attains its maximum value, on the interval $[0, 2]$. Find the value of $a$.
- Q12: Find the maximum and minimum values of $x + \sin 2x$ on $[0, 2\pi]$.
- Q13: Find two numbers whose sum is $24$ and whose product is as large as possible.
- Q14: Find two positive numbers $x$ and $y$ such that $x + y = 60$ and $xy^3$ is maximum.
- Q15: Find two positive numbers $x$ and $y$ such that their sum is $35$ and the product $x^2 y^5$ is a maximum.
- Q16: Find two positive numbers whose sum is $16$ and the sum of whose cubes is minimum.
- Q17: A square piece of tin of side $18$ cm is to be made into a box without top, by cutting a square from each corner and folding up the flaps to form the box. What should be the side of the square to be cut off so that the volume of the box is the maximum possible.
- Q18: A rectangular sheet of tin $45$ cm by $24$ cm is to be made into a box without top, by cutting off square from each corner and folding up the flaps. What should be the side of the square to be cut off so that the volume of the box is maximum ?
- Q19: Show that of all the rectangles inscribed in a given fixed circle, the square has the maximum area.
- Q20: Show that the right circular cylinder of given surface and maximum volume is such that its height is equal to the diameter of the base.
- Q21: Of all the closed cylindrical cans (right circular), of a given volume of $100$ cubic centimetres, find the dimensions of the can which has the minimum surface area?
- Q22: A wire of length $28$ m is to be cut into two pieces. One of the pieces is to be made into a square and the other into a circle. What should be the length of the two pieces so that the combined area of the square and the circle is minimum?
- Q23: Prove that the volume of the largest cone that can be inscribed in a sphere of radius $R$ is $\frac{8}{27}$ of the volume of the sphere.
- Q24: Show that the right circular cone of least curved surface and given volume has an altitude equal to $\sqrt{2}$ time the radius of the base.
- Q25: Show that the semi-vertical angle of the cone of the maximum volume and of given slant height is $\tan^{-1} \sqrt{2}$.
- Q26: Show that semi-vertical angle of right circular cone of given surface area and maximum volume is $\sin^{-1}(\frac{1}{3})$.
- Q27: The point on the curve $x^2 = 2y$ which is nearest to the point $(0, 5)$ is
- Q29: The maximum value of $[x(x-1)+1]^{\frac{1}{3}}$, $0 \le x \le 1$ is
CBSE Solutions for Class 12 Mathematics Application of Derivatives
Chapters in CBSE - Class 12 Mathematics
Top Tutors who teach Application of Derivatives
am geetha, from Chennai, a very dedicated and sincere professional from my end and I ensure that it is inculcated and reciprocated by the students as well. I have been in the teaching field since 2005 after my master's. I have tutored more 350 students in various batches and have boosted their confidence in Math, making the subject enjoyable for them. All of my past students have passed in flying colors and are flourishing in their professional careers now My class will be focused on strengthening the basic concepts and foundation that is essential to break down complex problems by using simple methods. I focus on clearing all the doubts step by step and conducting test papers after the completion of every lesson which will make it easier for the students to crack their school quarterly, half-yearly, and final exams with ease. Thank you, best regards from geetha Kumar.
Geetha Ma'am explains well and is ready to clear doubts. So far the experience has been very good and helpful to us.
​I am an experienced educator and founder of a dedicated coaching institute specializing in Class 12 tuition. With a strong track record of preparing students for board exams (CBSE), my focus is on building clear concepts and achieving top academic results. ​Key Experience & Skills ​Board Exam Specialization: Successfully guided numerous Class 12 batches, helping students consistently score 90%+ in board exams. ​Conceptual Learning: Focused on simplifying complex topics in Mathematics and Science through real-world examples rather than rote memorization. ​Structured Testing: Conduct regular chapter-wise tests, surprise quizzes, and full-length mock exams based on the latest board patterns. ​Doubt Resolution: Provided dedicated doubt-clearing sessions and individual attention to address every student's weak areas. ​Exam Strategies: Trained students in time management, answer-sheet presentation, and smart problem-solving techniques.
I learned many new things. Our teacher explained every topic in a simple and interesting way, which made learning easier for me. One day, our teacher conducted a fun quiz and group activity. Everyone participated enthusiastically, and we helped each other find the correct answers. It was a joyful moment because we learned something new while enjoying ourselves. My teacher appreciated my efforts, which boosted my confidence and motivated me to work harder. The friendly atmosphere of the coaching class made me feel comfortable asking questions and clearing my doubts. I also made good friends who supported me in my studies. This experience taught me the importance of teamwork, discipline, and regular practice. Overall, my coaching classes have given me not only academic knowledge but also confidence, friendship, and beautiful memories. It is one of the best experiences of my student life, and I will always remember it.
Teaching experience to students always feel challenging to me. Because every student has its own intellect power n grasping capability too. So understand them n teaching as per their ability is quite interesting. I love to teach those students who always try to grow themselves.
Really enjoying my Computer Science classes! The concepts are explained clearly, and even tricky topics feel easy to understand. The teaching is patient and interactive, and I feel more confident with every session. Highly recommended!
I am a dedicated tutor. I am having an experience of 12years in teaching accountancy through online as well as privately. I am teaching accountancy for 11, 12, B.Com, B.B.A, ACS, CA ICWA, CMA and all accountancy related courses. My students have fared well in their exams. My Approach is: 1.I will be teaching according to the students way. 2. I will clarify with the students having understood the topics and then only I will proceed to next topic. 3. Regular assessments given to students to know their progress.
Excellent coaching more patience and well experienced teaching my daughter now ready to learn happy. I think she get better knowledge of accountancy from shrimathi mam.
Working in an ICSE school and also Qualified Physics tutor (CTET, TNTET, PG TRB) teaching CBSE & ICSE students with clear explanations, interactive methods, and focused support to improve concepts, confidence, and results. I have helped nearly 30 plus students to overcome the fear of subjects especially physics.
The way of teaching is nice and clear explanation of teaching in theoretical and also practical is clear to understand.
Other Subjects in CBSE - Class 12
Download free CBSE - Class 12 Mathematics Application of Derivatives EXERCISE 6.3 worksheets
Download Now