Question 3 - Figure it out (Page 42, 43, 44) - Chapter 2 Class 7 - Arithmetic Expressions (Ganita Prakash)

Transcript

Question 3 (a) Find different ways of evaluating the following expressions: (a) 1 – 2 + 3 – 4 + 5 – 6 + 7 – 8 + 9 – 10Method 1: Group into pairs Group them two at a time (1 – 2) + (3 – 4) + (5 – 6) + (7 – 8) + (9 – 10) = (–1) + (–1) + (–1) + (–1) + (–1) = –5 Method 2: Separate + and – numbers Positive numbers: 1 + 3 + 5 + 7 + 9 = 25 Negative numbers: 2 + 4 + 6 + 8 + 10 = 30 Total: 25 – 30 = –5 Thus, Answer is –5 Question 3 (b) Find different ways of evaluating the following expressions: (b) 1 – 1 + 1 – 1 + 1 – 1 + 1 – 1 + 1 – 1 Method 1: Group into pairs Group them two at a time (1 – 1) + (1 – 1) + (1 – 1) + (1 – 1) + (1 – 1) = 0 + 0 + 0 + 0 + 0 = 0 Method 2: Separate + and – numbers Positive numbers: 1 + 1 + 1 + 1 + 1 = 5 Negative numbers: 1 + 1 + 1 + 1 + 1 = 5 Total: 5 – 5 = 0 Thus, Answer is 0 Thus, Answer is 0