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NCERT solution class 10 chapter 3 Pair of Linear Equations in Two Variables exercise 3.1 mathematics

EXERCISE 3.1


Page No 44:

Question 1:

Aftab tells his daughter, “Seven years ago, I was seven times as old as you were then. Also, three years from now, I shall be three times as old as you will be.” (Isn’t this interesting?) Represent this situation algebraically and graphically.

Answer:

Let the present age of Aftab be x.

And, present age of his daughter = y

Seven years ago,

Age of Aftab = x − 7

Age of his daughter = y − 7

According to the question,

Three years hence,

Age of Aftab = x + 3

Age of his daughter = y + 3

According to the question,

Therefore, the algebraic representation is

For ,

The solution table is

x

− 7

0

7

y

5

6

7

For ,

The solution table is

x

6

3

0

y

0

− 1

− 2

The graphical representation is as follows.


Question 3:

The cost of 2 kg of apples and 1 kg of grapes on a day was found to be Rs 160. After a month, the cost of 4 kg of apples and 2 kg of grapes is Rs 300. Represent the situation algebraically and geometrically.

Answer:

Let the cost of 1 kg of apples be Rs x.

And, cost of 1 kg of grapes = Rs y

According to the question, the algebraic representation is

For ,

The solution table is

x

50

60

70

y

60

40

20

For 4x + 2y = 300,

The solution table is

x

70

80

75

y

10

−10

0

The graphical representation is as follows.


 

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