Question

2x +5y =4
5x -7y = 3
solve by substitution method.​

Answer 1

Step-by-step explanation:

multiply equation 1 with 7

14x+35y=28

multiply equation 2 with 5

25x-35y=15

adding both equations

39x=43

x=43/39

putting in equation 1

86/39+5y=4

5y=4-86/39

5y=156-86/39

5y=70/39

y=14/39

Answer 2

Step-by-step explanation:

Given :-

2x +5y =4

5x -7y = 3

To find:-

Solve by substitution method?

Solution :-

Given equations are :

2x +5y =4 --------------(1)

5x -7y = 3 ------------ -(2)

=> 5x = 3+7y

=> x = (3+7y)/5 --------(3)

On Substituting the value of x in (1) then

=> 2[(3+7y)/5]+5y = 4

=> [(6+14y)/5]+5y = 4

=> (6+14y+25y)/5 = 4

=> (6+39y)/5 = 4

=> 6+39y = 4×5

=> 6+39y = 20

=> 39y = 20-6

=> 39y = 14

=> y = 14/39

On Substituting the value of y in (3)

=> x = (3+7(14/39))/5

=> x = (3+(98/39))/5

=> x = (117+98)/(39×5)

=> x = 215/195

=> x = 43/39

Therefore, x = 43/39 and y = 14/39

Answer:-

Solution for the given pair of linear equations in two variables is (43/39,14/39)

Check:-

If x = 43/39 and y = 14/39 then

LHS of (1) = 2(43/39)+5(14/39)

=> (86/39)+(70/39)

=>(86+70)/39

=> 156/39

=> 5

=>RHS

LHS = RHS

If x = 43/39 and y = 14/39 then

LHS of (2) = 5(43/39)-7(14/39)

=> (215/39)-(98/39)

=>(215-98)/39

=> 117/39

=> 3

=>RHS

LHS = RHS

Used Method:-

• Substitution method