Question

1. In a class test (+3) are given for every correct answer and (-2) marks are given for every incorrect answer and no marks for not attempting any questions.

(i) Sofia scored 20 marks. If she has got 12 correct answers, how many questions has she attempted incorrectly?

(ii) Milli scored -5 marks in the test, though she has got 7 correct answers. How many questions has she attempted incorrectly?

2 .Write down a pair of integers whose

(i) sum is -5
(ii) difference is -9
(iii) sum is 0

3 .If a=21, b = -11 and c = -5, verify that

(i) a + b = b + a
(ii) (a + b) + c = a + (b + c)

4. Write a pair of integers whose difference gives

(i) zero
(ii) a negative integer
(iii) an integer smaller than both the integers
(iv) an integer greater than both the integers

Answer 1

Answer:

1 answers

i . number of wrong answers is 8

ii . number of wrong answers is 13

2 answers

i . -2 and -3

ii . -1 and -8

iii . -1and +1

3 answers see in explanation

4 answers

i. 1 and -1

ii. -3 and 4

iii. 2 and 3

iv. -3 and -8

Step-by-step explanation:

I am going to show you the explanation of question 3 only .

Remember a = 21 , b = -11 and c = -5i .

a+b = b+a because addition is commutative i . 21+(-11)=-11+21

21-11=-11+21

10 = 10 so verified

ii . BODMAS (addition is commutative )

(a+b)+c =a(b+c)

(21 + (-11))+(-5)

=21+(-11+(-5))(21-11)-5

=21+(-11-5)10-5

=21-165=5 so verified

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