Question

3x+4y=12 and 7x+5y=2 solve linear equation by substitution method​ ( with out do LCM )​

Answer 1

Answer:

3x+4y=12 eq1 ×5

7x+5y=2 eq2 ×4

3x×5+4y×5=12×5

15×+20y=60 eq3

7x×4+5y×4=2×4

28x+20y=8 eq4

Substracting eq 4 and eq 3

15x+20y=60

28x+20y=8

-13x = 52

x = 52/-13

x = -4

Substituting x = -4 in eq 1

3x+4y=12

3×(-4)+4y=12

-12+4y=12

4y = 12/12

4y = 24

y = 24/4

y = 6

Therefore (x,y) = (-4,6) is the solution of given eq