Find the value of the following expressions, when x = -1:
(i) 2x - 7   (ii) - x + 2   (iii) x² + 2x + 1   (iv) 2x² - x - 2

Solution:

(i) 2x – 7

Since, it is given that x = -1

By substituting the value of x in the given expression, we get

= 2 × (-1) - 7

= - 2 - 7

= - 9

(ii) - x + 2

Since, it is given that x = -1

By substituting the value of x in the given expression, we get

= - (-1) + 2

= 1 + 2

= 3

(iii) x² + 2x + 1

Since, it is given that x = -1

By substituting the value of x in the given expression, we get

= (-1)² + 2 × (-1) + 1

= 1 - 2 + 1

= 2 - 2

= 0

(iv) 2x² – x – 2

Since, it is given that x = -1

By substituting the value of x in the given expression, we get

= 2 × (-1)² - (-1) - 2

= (2 × 1) + 1 – 2

= 2 + 1 – 2

= 3 – 2

= 1

☛ Check: NCERT Solutions for Class 7 Maths Chapter 12

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Video Solution:

Find the value of the following expressions, when x = –1: (i) 2x – 7 (ii) – x + 2 (iii) x² + 2x +1 (iv) 2x² – x – 2

 

Maths NCERT Solutions Class 7 Chapter 12 Exercise 12.3 Question 3

Summary:

The value of the following expressions, when x = –1: (i) 2x – 7 = - 9 (ii) – x + 2 = 3 (iii) x² + 2x + 1 = 0 (iv) 2x² – x – 2 = 1

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