 NCERT Exemplar Solution for CBSE Class 10 Mathematics: Quadratic Equations (Part-I)

In this article you will get CBSE Class 10 Mathematics chapter 4, Quadratic Equations: NCERT Exemplar Problems and Solutions (Part-I). Every question has been provided with a detailed solution. All the questions given in this article are very important to prepare for CBSE Class 10 Board Exam 2017-2018. Here you get the CBSE Class 10 Mathematics chapter 4, Quadratic Equations: NCERT Exemplar Problems and Solutions (Part-I). This part of the chapter includes solutions for Exercise 4.1 of NCERT Exemplar Problems for Class 10 Mathematics Chapter: Quadratic Equations. This exercise comprises of only the Multiple Choice Questions (MCQs) framed from various important topics in the chapter. Each question is provided with a detailed solution.

NCERT Exemplar problems are a very good resource for preparing the critical questions like Higher Order Thinking Skill (HOTS) questions. All these questions are very important to prepare for CBSE Class 10 Mathematics Board Examination 2017-2018 as well as other competitive exams.

Find below the NCERT Exemplar problems and their solutions for Class 10 Mathematics Chapter, Quadratic Equations:

Exercise 4.1

Multiple Choice Questions (MCQs)

Question1. Which of the following is a quadratic equation? Solution: (d)

Explanation:

An equation which is of the form ax2 + bx + c = 0, a ≠ 0 is called a quadratic equation. x3 - x2 = x3 -3x2 + 3x - 1

⟹-x2 + 3x2 - 3x + 1 = 0

⟹ 2x2 - 3x + 1 = 0

This equation is not of the form ax2+ bx + c, a ≠ 0. Thus, the equation is a quadratic equation.

Question2. Which of the following is not a quadratic equation?  This equation is not of the form ax2 + bx + c, a ≠ 0.

Thus, the equation is not quadratic.

Question3. Which of the following equations has 2 as a root?

(a) x2 -4x + 5 = 0

(b) x2 + 3x -12 = 0

(c) 2x2 -7x + 6 = 0

(d) 3x2 - 6x -2 = 0

Solution: (c)

Explanation:

If k is one of the root of any quadratic equation then x = k

i.e., k satisfies the equation ak2 + bk + c = 0.

i.e., f(k) = ak2 + bk + c = 0,

(a) Putting x = 2 in x2 - 4x + 5, we get

(2)2 - 4(2) + 5 = 4 - 8 + 5 = 1≠0.

So, x = 2 is not a root of x2 - 4x + 5 = 0.

(b) Putting x = 2 in x2 + 3x - 12, we get

(2)2 + 3(2) - 12 = 4 + 6 – 12 = –2 ≠ 0

So, x = 2 is not a root of x2 + 3x – 12 ≠ 0.

(c) Putting x = 2 in 2x2 – 7x + 6, we get

2(2)2 – 7(2) + 6 = 2 (4) – 14+ 6 = 8 – 14 + 6 = 14 – 14 = 0

So, x = 2 is root of the equation 2x2 – 7x + 6 = 0.

(d) Putting x = 2 in 3x2 –6x –2, we get

3(2)2 –6(2) –2 = 12 –12 –2 = –2 ≠ 0

So, x = 2 is not a root of 3x2 – 6x –2 = 0. k = 2

Question5. Which of the following equations has the sum of its roots as 3?  So, option (b) is correct.

Question6. Value(s) of k for which the quadratic equation 2x2kx + k = 0 has equal roots is/are

(a) 0

(b) 4

(c) 8

(d) 0, 8

Solution: (d)

Explanation:

For a quadratic equation of the form, ax2 + bx + c = 0, a ≠ 0 to have two equal real roots, its discriminant must be equal to zero, i.e., D = b2 –4ac = 0

Given equation is 2x2kx + k = 0

On comparing with ax2 + bx + c = 0, we get

a = 2, b = – k and c = k

For equal roots, the discriminant must be zero.

i.e., D = b2 – 4ac = 0

⟹ (– k)2 – 4 (2) k = 0

k2 – 8k = 0

k (k – 8) = 0

Thus, k = 0, 8

Hence, the required values of k are 0 and 8.     Question10. Which of the following equations has no real roots? Hence, the equation has two distinct real roots. Question11. (x2 + l)2x2 = 0 has

(a) four real roots

(b) two real roots

(c) no real roots

(d) one real root

Solution: (c) You may also like to read:

NCERT Solutions for CBSE Class 10 Maths