Page 2 - N.C.E.R.T PDF INTEGERS cl 7

2 MATHEMATICS

TRY THESE

1. A number line representing integers is given below

–3 and –2 are marked by E and F respectively. Which integers are marked by B,
D, H, J, M and O?
2. Arrange 7, –5, 4, 0 and – 4 in ascending order and then mark them on a number
line to check your answer.

We have done addition and subtraction of integers in our previous class. Read the
following statements.
On a number line when we
(i) add a positive integer, we move to the right.
(ii) add a negative integer, we move to the left.
(iii) subtract a positive integer, we move to the left.
(iv) subtract a negative integer, we move to the right.
State whether the following statements are correct or incorrect. Correct those which
are wrong:
(i) When two positive integers are added we get a positive integer.
(ii) When two negative integers are added we get a positive integer.
(iii) When a positive integer and a negative integer are added, we always get a negative
integer.
(iv) Additive inverse of an integer 8 is (– 8) and additive inverse of (– 8) is 8.
(v) For subtraction, we add the additive inverse of the integer that is being subtracted,
to the other integer.
(vi) (–10) + 3 = 10 – 3
(vii) 8 + (–7) – (– 4) = 8 + 7 – 4
Compare your answers with the answers given below:
(i) Correct. For example:
(a) 56 + 73 = 129 (b) 113 + 82 = 195 etc.

Construct five more examples in support of this statement.
(ii) Incorrect, since (– 6) + (– 7) = – 13, which is not a positive integer. The correct
statement is: When two negative integers are added we get a negative integer.

For example,
(a) (– 56) + (– 73) = – 129 (b) (– 113) + (– 82) = – 195, etc.
Construct five more examples on your own to verify this statement.