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Mon to Sat - 10 AM to 7 PM # Top 10 Questions in CBSE Class 12 Maths Exam - 2020

Check top 10 important maths questions and answers that will help you plan your study and revision in CBSE Class 12 Maths exam - 2020

By Topperlearning Expert 09th Mar, 2020 04:23 pm

Maths is a subject which requires practising a variety of problems to understand concepts clearly. By solving as many problems as you can, you’ll be able to train your brain in thinking the logical way to solve maths problems. To prepare for your Maths exam, you need to attempt solving different kinds of Maths questions.

The CBSE Class 12 Maths paper has 4 sections and is for 100 marks. The four sections are A, B, C and D, and the marks are distributed accordingly. Based on the past years’ papers and the frequency of a topic, our experts have made a list of top 10 questions that will help the students to score more in exams.

# Important Questions & Answers CBSE Class 12 Board Exam 2020 : Mathematics

1. Let N denote the set of all natural numbers and R be the relation on N × N defined by
(a, b) R (c, d) ⇔ ad(b + c) = bc(a + d). Prove that R is an equivalence relation on N × N.
Solution:
It is given that (a, b) R (c, d) ⇒ ad(b + c) = bc(a + d), where a, b, c, d ∊ N
First we need to check reflexivity of this function.
Now, (a, b) R (a, b) ⇒ ab(b + a) = ba(a + b), (a, b) ∊ N × N
Hence, R is reflexive relation.

Consider, (a, b) R (c, d) ⇒ ad(b + c) = bc(a + d), (a, b), (c, d) ∊ N × N
⇒ bc(a + d) = ad(b + c)
⇒ cb(d + a) = da(c + b)
⇒ (c, d) R (a, b)
Hence, R is symmetric relation.

(a, b) R (c, d) ⇒ ad(b + c) = bc(a + d), (a, b), (c, d) ∊ N × N
⇒ (1/c) + (1/b) = (1/d) + (1/a)
⇒ (1/a) - (1/b) = (1/c) - (1/d)
(c, d) R (e, f) ⇒ cf(d + e) = de(c + f), (c, d), (e, f) ∊ N × N
⇒ (1/c) - (1/d) = (1/e) - (1/f)
Now,
⇒ (1/a) - (1/b) = (1/c) - (1/d) and (1/c) - (1/d) = (1/e) - (1/f)
⇒ (1/a) - (1/b) = (1/e) - (1/f)
⇒ af(b + e) = be(a + f)
⇒ (a, b) R (e, f)
Hence, R is transitive relation.
Thus, R is an equivalence relation.

2. Show that 3. Using elementary transformations, find the inverse of the following matrix : 4. Find derivative of (log x)x + xlog x.

5. 6. Show that semi-vertical angle of right circular cone of given surface area and maximum volume is . 7.  A tank with rectangular base and rectangular sides, open at the top is to be constructed so that its depth is 2 m and volume is 8 m3. If building of tank costs Rs. 70 per sq. metres for the base and Rs. 45 per square metre for sides. What is the cost of least expensive tank?

8.  Evaluate: 9. Integrate 10. Integrate ## Review all the important answers and practice material for CBSE Class 12 Matsh exam 2020 here:

CBSE Class 12 Maths Exam 2020 - Sample Papers

CBSE Class 12 Maths Exam 2020 - Previous years papers

CBSE Class 12 Maths Exam 2020 – Text book solutions

CBSE Class 12 Maths Exam 2020 – Revision notes

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