CBSE Notes, Lectures

CBSE - Mathematics - Pair of Linear Equations in Two Variables

Pair of Linear Equations in Two Variables

NCERT Exercise Exercise 3.1

The coach of a cricket team buys 3 bats and 6 balls for Rs 3900. Later, she buys another bat and 3 more balls of the same kind for Rs 1300. Represent this situation algebraically and geometrically

 

Let cost of one bat = Rs x
Cost of one ball = Rs y
3 bats and 6 balls for Rs 3900 So that
3+ 6y = 3900 … (i)
Dividing equation by 3, we get
+ 2y = 1300
Subtracting 2y both side we get
x = 1300 – 2
Putting y = -1300, 0 and 1300 we get
x = 1300 – 2 (-1300) = 1300 + 2600 = 3900
= 1300 -2(0) = 1300 - 0 = 1300
x = 1300 – 2(1300) = 1300 – 2600 = - 1300
 

x 3900 1300 -1300
y -1300 0 1300


Given that she buys another bat and 2 more balls of the same kind for Rs 1300
So, we get
x + 2= 1300 … (ii)
Subtracting 2y both side we get
= 1300 – 2y
Putting y = - 1300, 0 and 1300 we get
x = 1300 – 2 (-1300) = 1300 + 2600 = 3900
= 1300 – 2 (0) = 1300 - 0 = 1300
= 1300 – 2(1300) = 1300 – 2600 = -1300
 

x 3900 1300 -1300
y -1300 0 1300


Algebraic representation
3+ 6y = 3900 … (i)
+ 2= 1300 … (ii)
Graphical representation,

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