RS Aggarwal Class 9 Math Chapter 2 Polynomials Exercise 2I Solution

EXERCISE 2I

Question 1:
(i) (3x + 2)3
= (3x)3 + (2)3 + 3 × 3x × 2 (3x + 2)
RS Aggarwal Solutions Class 9 Chapter 2 Polynomials 2i 1.1
= 27x3 + 8 + 18x (3x + 2)
= 27x3 + 8 + 54x2 + 36x.
(ii) (3a – 2b)3
= (3a)3 – (2b)3 – 3 × 3a × 2b (3a – 2b)
RS Aggarwal Solutions Class 9 Chapter 2 Polynomials Q1.1
= 27a3 – 8b3 – 18ab (3a – 2b)
= 27 a3 – 8b3 – 54a2b + 36ab2.
RS Aggarwal Solutions Class 9 Chapter 2 Polynomials 2i 1.2

Question 2:
RS Aggarwal Solutions Class 9 Chapter 2 Polynomials 2i 2.1

Question 3:
(i) (95)3
= (100 – 5)3
= (100)3 – (5)3 – 3 × 100 × 5 (100 – 5)
= 1000000 – 125 – (1500 95)
= 857375.
(ii) (999)3
= (1000 – 1)3
= (1000)3 – (1)3 – 3 × 1000 × 1 (1000 – 1)
= 1000000000 – 1 – 3000 (1000 – 1)
= 1000000000 – 1 – (3000 999)
= 997002999.