(a) Simplify 3x(4x - 5) + 3 and find its values for (i) x = 3 (ii) x = 1/2 
(b) Simplify a (a² + a + 1)+ 5 and find its values for (i) a = 0, (ii) a =1, (iii) a = - 1

Solution:

(a) 3x (4x - 5) + 3

= 12x² -15x + 3

(i) For x = 3,

= 12x² -15x + 3

= 12(3)² -15(3) + 3

= 108 - 45 + 3

= 66

(ii) For x = 1/2

= 12x² -15x + 3

= 12(1/2)² - 15(1/2) + 3

= 3 - 15/2 + 3

= -3/2

(b)a (a² + a + 1) + 5 = a³ + a² + a + 5

(i) For a = 0,

a³ + a² + a + 5

= 0 + 0 + 0 + 5 = 5

(ii) For a = 1,

a³ + a² + a + 5

= (1)³ + (1)² + 1 + 5

= 1 + 1 + 1 + 5 = 8

(iii) For a = -1,

a³ + a² + a + 5

= (-1)³ + (-1)² + (-1) + 5

= - 1 + 1 -1 + 5 = 4

☛ Check: NCERT Solutions for Class 8 Maths Chapter 9

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Video Solution:

(a) Simplify 3x(4x - 5) + 3 and find its values for (i) x = 3 (ii) x = 1/2  (b) Simplify a (a² + a + 1)+ 5 and find its values for (i) a = 0, (ii) a =1, (iii) a = - 1

NCERT Solutions Class 8 Maths Chapter 9 Exercise 9.3 Question 4

Summary:

(a) Simplify 3x(4x - 5) + 3 and find its values for (i) x = 3 (ii) x = 1/2  (b) Simplify a (a² + a + 1)+ 5 and find its values for (i) a = 0, (ii) a =1, (iii) a = - 1. The expressions are simplified and corresponding values are: (a) 12x² -15x + 3 (i) 66, (ii) -3/2 and (b) a³ + a² + a + 5 (i) 5, (ii) 8, and (iii) 4.

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