Question

Solve the following systems by 'Elmination by Substitution method.'
x/7+y/5=10/7 ; x+y/3=14/3
The answer is x=3 ,y= 5
Class 10th

Answer 1

Hi dear your answer is given .

....................................................................................

x/7+y/5=10/7.

5x+7y/35 = 10/7
5x+7y = 10*35/7
5x+7y = 10*5
5x+7y = 50.

x+y/3 = 14/3.
3x+y/3 = 14/3
3x+y = 14*3/3
3x+y = 14.

5x+7y = 50. ( Equ. 1st )
3x+y = 14. ( Equ. 2nd)

In Elimination Method.

multiply by (1) in equ. 1st and (7) in equ. 2nd we get

5x+7y = 50. (Equ. 4th )
21x+7y = 98. (Equ. 5th )
(-) (-) = (-)
____________
-16x = -48
x= -48/-16
x = 3.

put the value of X in equ. 2nd we will get the value of Y.

3x+y = 14
3*3 + y = 14. (x = 3)
9+y = 14
y = 14-9
y = 5.

[X = 3 , Y = 5].

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In Substitution Method.

5x+7y = 50. ( 1st. )

3x+y = 14. ( 2nd. )

3x+y=14
3x = 14-y

x = 14-y/3

put the value of X in equ. 1st

5x+7y = 50
5(14-y/3)+7y = 50
70-5y/3+7y = 50
70-5y+21y/3 = 50
70-5y+21y = 50*3
70+16y = 150
16y = 150-70
16y = 80
y = 80/16
y = 5.

put the value of Y in equ. 2nd we will get the value of X.

3x+y = 14
3x+5 = 14. (y = 5)
3x = 14-5
3x = 9
x = 9/3
x = 3.

[X = 3 , Y = 5]


it will help completely dear .

u will understand.


if you will like the answer then mark as brain list.

#THANKS #.