Question

Solve the following pair of linear equations by Substitution method:

5x+3y=11

2x-7y=-12 ( 3 marks)

Answer 1

Step 1:

5x+3y=11 -------------------------------------(1)

⇒3y=11-5x

⇒y=(11-5x)/3 ---------------------------------(2)

Given, 2x-7y=-12 ------------------------------(3) ( 1 mark)

Step 2:

Using value of y in equation (3), we get

2x-7((11-5x)/3 )=-12

⇒2x-(77-35x)/3= -12

⇒ (6x-77+35x)/3= -12

⇒41x-77=-36

⇒41x=41

⇒x=1 ( 1 mark)

Putting x=1in equation (2), we get

y=(11-5×1)/3

⇒y= 6/3

⇒y=2

Therefore the required solutions are
x=1, y=2 ( 1mark)