Question

solve the following pairs of linear equations by substitution method (a) 2x-y=1 (b) 5x+2y=25​

Answer 1

Answer :

x = 3 , y = 5

Solution :

Here ,

The given linear equations are ;

2x - y = 1 ------(1)

5x + 2y = 25 --------(2)

Using eq-(1) , we have ;

=> 2x - y = 1

=> y = 2x - 1 -------(3)

Now ,

Putting y = 2x - 1 in eq-(2) , we have ;

=> 5x + 2y = 25

=> 5x + 2(2x - 1) = 25

=> 5x + 4x - 2 = 25

=> 5x + 4x = 25 + 2

=> 9x = 27

=> x = 27/9

=> x = 3

Now ,

Putting x = 3 in eq-(3) , we have ;

=> y = 2x - 1

=> y = 2•3 - 1

=> y = 6 - 1

=> y = 5

Hence ,

x = 3 and y = 5 .

Answer 2

Answer:

a)2x-y=1

=2x+2.1-y

=2x+2×1-y

=2x+1-y

=2x-1y

=1

b)5x+2y=25

=5x+1.5-25

=5x+5-25

=25-0