Samacheer Kalvi 7th Maths Solutions Term 1 Chapter 1 Number System Ex 1.1
Samacheer Kalvi 7th Maths Solutions Term 1 Chapter 1 Number System Ex 1.1
Tamilnadu Samacheer Kalvi 7th Maths Solutions Term 1 Chapter 1 Number System Ex 1.1
samacheer kalvi 7th maths book solutions Question 1.
Fill in the blanks:
(i) (-30) + ____ = 60
(ii) (-5) + ___ = -100
(iii) (-52) + (-52) = ____
(iv) ____ + (-22) = 0
(v) ____ + (-70) = 70
(vi) 20 + 80 + ___ = 0
(vii) 75 + (-25) = ____
(viii) 171 + ___ = 0
(ix) [(-3) + (-12)] + (-77) = _____ + [(12) + (-77)]
(x) (-42) + [____ + (-23)] = [____ + 15] + ____
Solution:
(i) 90
(ii) -95
(iii) -104
(iv) 22
(v) 140
(vi) -100
(vii) 50
(viii) -171
(ix) -3
(x) +15; -42; -23
7th standard maths exercise 1.1 Question 2.
Say True or False.
(i) The additive inverse of (-32) is -32
(ii) (-90) + (-30) = 60
(iii) (-125) + 25 = -100
Solution:
(i) False
(ii) False
(iii) True
7th standard maths number system exercise 1.1 Question 3.
Add the following.
(i) 8 and-12 using number line.
Solution:
Starting at zero on the number line facing positive direction and move 8 steps forward reaching 8.
Then we move 12 steps
backward to represent -12 –
and reach at -4.
∴ 8 + (-12) = -4
(ii) (-3) and (-5) using number line.
Solution:
Starting at zero on the number line facing positive direction and move 3 steps backward reaching-3.
Then we move 5 steps backward to represent -5 and reach -8.
∴ (-3) + (-5) = -8
(iii) (-100) + (-10)
Solution:
(-100) + (-10) = -100 – 10 = -110
(iv) 20 + (-72)
Solution:
20 + (-72) = 20 – 72 = -52
(v) 82 + (-75)
Solution:
82 + (-75) = 82 – 75 = 7
(vi) -48 + (-15)
Solution:
-48 + (-15) = -48 – 15 = -63
(vii) -225 + (-63)
Solution:
-225 + (-63) = -225 – 63 = -288
samacheer kalvi guru 7th maths Question 4.
Thenmalar appeared for competitive exam which has negative scoring of 1 mark for each incorrect answers. In paper I she answered 25 question incorrectly and in paper II13 questions incorrectly. Find the total reduction of marks.
Solution:
For each incorrect question the score = -1
In paper I, score for 25 incorrect questions – 25 × (-1) = -25
In paper II, for 13 incorrect question the score = 13 × (-1) = -13
The total marks get reduced = (-25) + (-13) = -38
-38 marks will be reduced.
samacheer kalvi 7th maths book answers Question 5.
In a quiz competition, Team A scored +30, -20, 0 and team B scored -20, 0,+30 in three successive rounds. Which team will win? Can we say that we can add integers in any order?
Solution:
Total score of team A = [(+30) + (-20)] + 0 = (+10) + 0 = 10
Total score of team B = [(-20) + 0] + (+30)
= -20 + 30 = +10
Score of team A = Score of team B.
Yes, we say that we can add integers in any order.
7th std samacheer kalvi maths solutions Question 6.
Are (11 + 7) +10 and 11 + (7 + 10) equal? Mention the property.
Solution:
First we take (11 + 7) + 10 = 18 + 10 = 28
Now 11 + (7 + 10) = 11 + 17 = 28
In both the cases the sum is 28. ∴ (11 + 7) + 10 = 11 + (7 + 10)
This property is known as associative property of integers under addition.
samacheer kalvi 7th maths solutions Question 7.
Find 5 pairs of integers that added to 2.
Solution:
0 + 2 = 2
1 + 1 = 2
-1+3 = 2
-2 + 4 = 2
-3 + 5 =2 (and many more.)
Objective Type Questions
7th maths solution samacheer kalvi Question 8.
The temperature at 12 noon at a certain place was 18° above zero. If it decreases at the rate of 3° per hour at what time if would be 12° below zero?
(i) 12 mid night
(ii) 12 noon
(iii) 10 am
(iv) 10 pm
Solution:
(iv) 10 pm
: ’Temperature at 12 noon = 18° above zero = +18°
Rate of decrease per hour = -3°
Temperature 12° below zero = -12°
-12 is 30 units to the left of+18°
Time at which it reach -12° = 30/3 = 10 h
10 hrs after 12 noon = 10 pm
7th maths guide term 1 Question 9.
Identify the problem with negative numbers as its answer.
(i) -9 +(-5) + 6
(ii) 8 + (-12) – 6
(iii) -4 + 2 + 10
(iv) 10 + (-4) + 8
Solution:
(i) -9 +(-5) + 6
(i) -9 + (-5) + 6 = -14 + 6 = -8
(ii) 8 + (-12) + 6 = -4 + 6 = – 2
(iii) -4 + 2 + 10 = -2 + 10 = 8
(iv) 10 + (-4) + 8 = 6 + 8 = 14
7th maths exercise 1.1 Question 10.
(-10) + (+7) = ____
(i) +3
(ii) -3
(iii) -17
(iv) +17
Solution:
(ii) -3
7th standard maths book exercise 1.1 Question 11.
(-8) + 10 + (-2) = ____
(i) 2
(ii) 8
(iii) 0
(iv) 20
Solution:
(iii) 0
samacheer kalvi.guru 7th Question 12.
20 + (-9) + 9 = ____
(i) 20
(ii) 29
(iii) 11
(iv) 38
Solution:
(i) 20
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