- NCERT Solutions for Class 7 Maths Chapter 1 Integers Ex 1.1
- NCERT Solutions for Class 7 Maths Chapter 1 Integers Ex 1.2
- NCERT Solutions for Class 7 Maths Chapter 1 Integers Ex 1.3
NCERT Solutions for Class 7 Maths Chapter 1 Integers Ex 1.2 (Rationalised Contents)
Ex 1.2 Class 7 Maths Question 1.
Find each of the following products:
(a) 3 × (-1)
(b) (-1) × 225
(c) (-21) × (-30)
(d) (-316) × (-1)
(e) (-15) × O × (-18)
(f) (-12) × (-11) × (10)
(g) 9 x (-3) × (-6)
(h) (-18) × (-5) × (-4)
(i) (-1) × (-2) × (-3) × 4
(j) (-3) × (-6) × (-2) × (-1)
Solution.
(a) 3 × (-1) = – (3 × 1) = -3
(b) (-1) × 225 = – (1 × 225) = -225
(c) (-21) × (-30) = 21 × 30 = 630
(d) (-316) × (-1) = 316 × 1 = 316
(e) (-15) × 0 × (-18) = [(-15) × 0] × (-18) = 0 × (-18) = 0
(f) (-12) × (-11) × (10) = [(-12) × (-11)] × (10)
= (132) × (10) = 1320
(g) 9 × (-3) × (-6) = [9 × (-3)] × (-6) = (-27) × (-6) = 162
(h) (-18) × (-5) × (-4) = [(-18) × (-5)] × (-4)
= 90 × (-4) = -360
(i) (-1) × (-2) × (-3) × 4 = [(-1) × (-2)] × [(-3) × 4]
= (2) × (-12) = -24
(j) (-3) × (-6) × (-2) × (-1) = [(-3) × (-6)] × [(-2) × (-1)] = (18) × (2) = 36
Ex 1.2 Class 7 Maths Question 2.
Verify the following:
(a) 18 × [7 + (-3)] = [18 × 7] + [18 × (-3)]
(b) (-21) × [(-4) + (-6)] = [(-21) × (-4)] + [(-21) × (-6)]
Solution.
(a) We have,
LHS = 18 × [7 + (-3)] = 18 × 4 = 72
RHS = [18 × 7] + [18 × (-3)] = 126 – 54 = 72
18 × [7 + (-3)] = [18 × 7] + [18 × (-3)]
(b) We have,
LHS = (-21) × [(-4) + (-6)] = (-21) × (-4 – 6) = (-21) (-10) = 210
RHS = [(-21) × (-4) + [(-21) × (-6)] = 84 + 126 = 210
∴ (-21) × [(-4) + (-6)] = [(-21) × (-4)] + [(-21) × (-6)]
Ex 1.2 Class 7 Maths Question 3.
(i) For any integer a, what is (-1) × a equal to?
(ii) Determine the integer whose product with (-1) is
(a) -22
(b) 37
(c) 0
Solution.
(i) For any integer a, (-1) × a = -a.
(ii) We know that the product of any integer and (-1) is the additive inverse of the integer. The integer whose product with (-1) is
(a) -22 is the additive inverse of -22, i.e., 22.
(b) 37 is the additive inverse of 37, i.e., -37.
(c) 0 is the additive inverse of 0, i.e., 0.
Ex 1.2 Class 7 Maths Question 4.
Starting from (-1) × 5, write various products showing some pattern to show (-1) × (-1) = 1.
Solution.
(-1) × 5 = -5
(-1) × 4 = -4 = [-5 – (-1)] = -5 + 1
(-1) × 3 = -3 = [-4 – (-1)] = -4 + 1
(-1) × 2 = -2 = [-3 – (-1)] = -3 + 1
(-1) × 1 = -1 = [-2 – (-1)] = -2 + 1
(-1) × 0 = 0 = [-1 – (-1)] = -1 + 1
(-1) × (-1) = [0 – (-1)] = 0 + 1 = 1
Related Links:
NCERT Solutions for Maths Class 8
NCERT Solutions for Maths Class 9
NCERT Solutions for Maths Class 10