RS Aggarwal Solutions for Class 8 Maths Chapter 7 Exercise 7.2: The solutions for RS Aggarwal's Class 8 Maths Chapter 7 Exercise 7.2 prepared by the subject experts of Physics Wallah, provide a thorough and insightful guide to factorization problems.
These expert-prepared solutions provide a clear and detailed breakdown of each problem, ensuring that students can follow along and understand the factorization process. The explanations cover various techniques and approaches helping students master the key concepts required to solve the exercise effectively.RS Aggarwal Solutions for Class 8 Maths Chapter 7 Exercise 7.2 PDF
Factorise:
(Question 1) x 2 – 36
= x 2 – 6 2 = (x – 6) (x + 6)(Question 2) 4a 2 – 9
= (2a) 2 – (3) 2 = (2a – 3) (2a + 3)(Question 3) 81 – 49x 2
= (9) 2 – (7x) 2 = (9 – 7x) (9 + 7x)(Question 4) 4x 2 – 9y 2
= (2x) 2 – (3y) 2 = (2x – 3y) (2x + 3y)(Question 5) 16a 2 – 225b 2
= (4a) 2 – (15b) 2 = (4a – 15b) (4a + 15b)(Question 6) 9a 2 b 2 – 25
= (3ab) 2 – (5) 2 = (3ab – 5) (3ab + 5)(Question 7) 16a 2 – 144
= (4a) 2 – (12) 2 = (4a – 12) (4a + 12) = [4(a – 3)] [4(a + 3)] = (4 × 4) (a – 3) (a + 3) = 16 (a – 3) (a + 3)(Question 8) 63a 2 – 112b 2
= 7(9a 2 – 16b 2 ) = 7 [(3a) 2 – (4b) 2 ] = 7 (3a – 4b) (3a + 4b)(Question 9) 20a 2 – 45b 2
= 5(4a 2 – 9b 2 ) = 5 [(2a) 2 – (3b) 2 ] = 5 (2a – 3b) (2a + 3b)(Question 10) 12x 2 – 27
= 3(4x 2 – 9) = 3[(2x) 2 – (3) 2 ] = 3 (2x – 3) (2x + 3)(Question 11) x 3 – 64x
= x[(x) 2 – (8) 2 ] = x (x – 8) (x + 8)(Question 12) 16x 5 – 144x 3
= 16x 3 (x 2 – 9) = 16x 3 [(x) 2 – (3) 2 ] = 16x 3 (x – 3) (x + 3)(Question 13) 3x 5 – 48x 3
= 3x 3 [(x) 2 – 16] = 3x 3 [(x) 2 – (4) 2 ] = 3x 3 (x – 4) (x + 4)(Question 14) 16p3 – 4p
= 4p (4p 2 – 1) = 4p [(2p) 2 – (1) 2 ] = 4p (2p – 1) (2p + 1)(Question 15) 63a 2 b 2 – 7
= 7 (9a 2 b 2 – 1) = 7 [(3ab) 2 – (1) 2 ] = 7 (3ab – 1) (3ab + 1)(Question 16) 1 – (b – c) 2
= (1) 2 – (b – c) 2 = (1 – b + c) (1 + b – c)(Question 17) (2a + 3b) 2 – 16c 2
= (2a + 3b) 2 – (4c) 2 = (2a + 3b – 4c) (2a + 3b + 4c)(Question 18) (l + m) 2 – (l – m) 2
= (l + m + l – m) (l + m – l + m) = 2l × 2m = 4lm(Question 19) (2x + 5y) 2 – 1
= (2x + 5y) 2 – (1) 2 = (2x + 5y – 1) (2x + 5y + 1)(Question 20) 36c 2 – (5a + b) 2
= (6c) 2 – (5a + b) 2 = (6c + 5a + b) (6c – 5a – b)(Question 21) (3x – 4y) 2 – 25z 2
= (3x – 4y) 2 – (5z) 2 = (3x – 4y + 5z) (3x – 4y – 5z)(Question 22) x 2 – y 2 – 2y – 1
= x 2 – (y 2 + 2y + 1) = x 2 – (y + 1) 2 = (x + y + 1) (x – y – 1)(Question 23) 25 – a 2 – b 2 – 2ab
= 25 – (a 2 + 2ab + b 2 ) = (5) 2 – (a + b) 2 = (5 + a + b) (5 – a – b)(Question 24) 25a 2 – 4b 2 + 28bc – 49c 2
= 25a 2 – [(2b) 2 – (2 × 2b × 7c) + (7c) 2 ] = (5a) 2 – (2b – 7c) 2 = (5a + 2b – 7c) (5a – 2b + 7c)(Question 25) 9a 2 – b 2 + 4b – 4
= 9a 2 – [(b) 2 – (2 × b × 2) + (2) 2 ] = (3a) 2 – (b – 2) 2 = (3a + b – 2) (3a – b + 2)(Question 26) 100 – (x – 5) 2
= (10) 2 – (x – 5) 2 = (10 + x – 5) (10 – x + 5) = (5 + x) (15 – x)(Question 27) Evaluate {(405) 2 – (395) 2 }
= (405 + 395) (405 – 395) = 800 × 10 = 8000(Question 28) Evaluate {(7.8) 2 – (2.2) 2 }
= (7.8 + 2.2) (7.8 – 2.2) = 10 × 5.6 = 56