Mathematics NCERT class 7 chapter 1 exercise 1.2 solutions
NCERT maths class 7 chapter 1 exercise 1.2 solutions are given.
You should study the textbook lesson Integers very well.
You should also practice all problems and solutions are given in the textbook.
Observe the solutions and try them in your own method.
NCERT maths class 7 solutions
Exercise 1.1
Integers Exercise 1.2 solutions NCERT maths class 7
chapter 1
Integers
Exercise 1.2
1. Find each of the following products:
a. 3 × ( -1)
b. (- 1) × 225
c. (- 21) × (- 30)
d. (- 316) × (- 1)
e. (- 15) × 0 × (- 18)
f. (- 12) × (- 11) × (10)
g. 9 × (- 3) × (- 6)
h. (- 18) × (- 5) × (- 4)
i. (- 1) × (- 2) × (- 3) × 4
j. (- 3) × (- 6) × (- 2) × (- 1)
Solutions:
a. 3 × (- 1) = – 3
b. (- 1) × 225 = – 225
c. (- 21) × (- 30) = 630
d. (- 316) × (- 1) = 316
e. (- 15) × 0 × (- 18) = 0
f. (- 12) × (- 11) × (10) = 1320
g. 9 × (- 3) × (- 6) = 9 × 18 = 162
h. (- 18) × (- 5) × (- 4)
(- 18) × [ (- 5) × (- 4)]
= – 18 × 20 = – 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
Problem:
2. Verify the following:
a. 18 × [ 7 + (- 3)] = [ 18 × 7] + [ 18 × (- 3)]
b. (- 21) × [ (- 4) + (- 6)] = [ (- 21) × (- 4) + [ (- 21) × (- 6)]
Solution:
a. 18 × [ 7 + (- 3)] = [ 18 × 7] + [ 18 × (- 3)
18 × [ 7 + (- 3)] = 18 × (7 – 3) = 18 × 4 = 72
[ 18 × 7] + [ 18 × (- 3)] = (126) + (- 54) = 126 – 54 = 72
Therefore, 18 × [ 7 + (- 3)] = [ 18 × 7] + [ 18 × (- 3)]
b. (- 21) × [ (- 4) + (- 6)] = [ (- 21) × (- 4)] + [ (- 21) × (- 6)]
(- 21) × [ (- 4) + (- 6)] = (- 21) × [ – 4 – 6] = (- 21) × (- 6) = 210
[ (- 21) × (- 4)] + [ (- 21) × (- 6)] = [ 84] + [ 126] = 210
Problems:
3. i. For any integer a, what is (- 1) × an equal to?
ii. Determine the integer whose product with (- 1) is.
a. – 22
b. 37
c. 0
Solutions:
i. For any integer a, (- 1) × a = – a
ii. a. (- 1) × (- 22) = 22
b. (- 1) × (- 37) = – 37
c. (- 1) × (0) = 0
Problem:
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
(- 1) × 3 = – 3 = – 4 + 1
(- 1) × 2 = – 2 = – 3 + 1
(- 1) × 1 = – 1 = – 2 + 1
(- 1) × 0 = – 0 = – 1 + 1
So, (- 1) × (- 1) = 1 = 0 + 1
Note: Observe the solutions and try them in your own method.
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