Page 1 Exercise 5.2 PAGE: 5.9 1. Draw a number line and represent each of the following on it: (i) 5 + (-2) (ii) (-9) + 4 (iii) (-3) + (-5) (iv) 6 + (-6) (v) (-1) + (-2) + 2 (vi) (-2) + 7 + (-9) Solution: (i) 5 + (-2) From 0 move towards right of first five units to obtain + 5 So the second number is – 2 so move 2 units towards left of + 5 we get + 3 Therefore, 5 + (-2) = 3. (ii) (-9) + 4 From 0 move towards left of nine units to obtain – 9 So the second number is 4 so move 4 units towards right of – 9 we get – 5 Therefore, (-9) + 4 = - 5. (iii) (-3) + (-5) From 0 move towards left of three units to obtain – 3 So the second number is – 5 so move 5 units towards left of – 3 we get – 8 Therefore, (-3) + (-5) = - 8. Page 2 Exercise 5.2 PAGE: 5.9 1. Draw a number line and represent each of the following on it: (i) 5 + (-2) (ii) (-9) + 4 (iii) (-3) + (-5) (iv) 6 + (-6) (v) (-1) + (-2) + 2 (vi) (-2) + 7 + (-9) Solution: (i) 5 + (-2) From 0 move towards right of first five units to obtain + 5 So the second number is – 2 so move 2 units towards left of + 5 we get + 3 Therefore, 5 + (-2) = 3. (ii) (-9) + 4 From 0 move towards left of nine units to obtain – 9 So the second number is 4 so move 4 units towards right of – 9 we get – 5 Therefore, (-9) + 4 = - 5. (iii) (-3) + (-5) From 0 move towards left of three units to obtain – 3 So the second number is – 5 so move 5 units towards left of – 3 we get – 8 Therefore, (-3) + (-5) = - 8. (iv) 6 + (-6) From zero move towards right of six units to obtain 6 So the second number is – 6 so move 6 units towards left of 6 we get 0 Therefore, 6 + (-6) = 0. (v) (-1) + (-2) + 2 From zero move towards left of one unit to obtain – 1 So the second number is – 2 so move 2 units towards left of – 1 we get – 3 The third number is 2 so move 2 units towards right of – 3 we get – 1 Therefore, (-1) + (-2) + 2 = - 1. (vi) (-2) + 7 + (-9) From zero move towards left of two units to obtain – 2 So the second number is 7 so move 7 units towards right of – 2 we get 5 The third number is – 9 so move 9 units towards left of 5 we get – 4 Therefore, (-2) + 7 + (-9) = - 4. 2. Find the sum of (i) -557 and 488 (ii) -522 and -160 (iii) 2567 and – 325 (iv) -10025 and 139 (v) 2547 and -2548 (vi) 2884 and -2884 Page 3 Exercise 5.2 PAGE: 5.9 1. Draw a number line and represent each of the following on it: (i) 5 + (-2) (ii) (-9) + 4 (iii) (-3) + (-5) (iv) 6 + (-6) (v) (-1) + (-2) + 2 (vi) (-2) + 7 + (-9) Solution: (i) 5 + (-2) From 0 move towards right of first five units to obtain + 5 So the second number is – 2 so move 2 units towards left of + 5 we get + 3 Therefore, 5 + (-2) = 3. (ii) (-9) + 4 From 0 move towards left of nine units to obtain – 9 So the second number is 4 so move 4 units towards right of – 9 we get – 5 Therefore, (-9) + 4 = - 5. (iii) (-3) + (-5) From 0 move towards left of three units to obtain – 3 So the second number is – 5 so move 5 units towards left of – 3 we get – 8 Therefore, (-3) + (-5) = - 8. (iv) 6 + (-6) From zero move towards right of six units to obtain 6 So the second number is – 6 so move 6 units towards left of 6 we get 0 Therefore, 6 + (-6) = 0. (v) (-1) + (-2) + 2 From zero move towards left of one unit to obtain – 1 So the second number is – 2 so move 2 units towards left of – 1 we get – 3 The third number is 2 so move 2 units towards right of – 3 we get – 1 Therefore, (-1) + (-2) + 2 = - 1. (vi) (-2) + 7 + (-9) From zero move towards left of two units to obtain – 2 So the second number is 7 so move 7 units towards right of – 2 we get 5 The third number is – 9 so move 9 units towards left of 5 we get – 4 Therefore, (-2) + 7 + (-9) = - 4. 2. Find the sum of (i) -557 and 488 (ii) -522 and -160 (iii) 2567 and – 325 (iv) -10025 and 139 (v) 2547 and -2548 (vi) 2884 and -2884 Solution: (i) -557 and 488 We get -557 + 488 It can be written as |-557| - |488| = 557 – 488 = 69. (ii) -522 and -160 We get -522 + (-160) It can be written as -522 – 160 = - 682 (iii) 2567 and – 325 We get 2567 + (-325) It can be written as 2567 – 325 = 2242 (iv) -10025 and 139 We get -10025 + 139 It can be written as -10025 + 139 = -9886 (v) 2547 and -2548 We get 2547 + (-2548) It can be written as 2547 – 2548 = -1 (vi) 2884 and -2884 We get 2884 + (-2884) It can be written as 2884 – 2884 = 0Read More

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