If 2x + 4y = 5 and 4x + 2y =7, then what is the value of x + y? *
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Answer :-
Method I :-
→ 2x + 4y = 5 -i
→ 4x + 2y = 7 -ii
Adding both the equations :-
→ 2x + 4y + 4x + 2y = 7 + 5
→ 2x + 4x + 4y + 2y = 12
→ 6x + 6y = 12
→ 6 ( x + y ) = 12
→ x + y = 12 / 6
→ x + y = 2
Method II :-
→ 2x + 4y = 5 -i
→ 4x + 2y = 7 -ii
Multiplying equation i by 2 :-
→ 2 ( 2x + 4y = 5 )
→ 4x + 8y = 10 -iii
Subtracting equation i by iii :-
→ 4x + 8y - 4x - 2y = 10 - 7
→ 6y = 3
→ y = ½
Substituting the value in equation i :-
→ 2x + 4y = 5
→ 2x + 4 × ½ = 5
→ 2x + 2 = 5
→ 2x = 3
→ x = 3 / 2
x + y = 3 / 2 + 1 / 2 = 4 / 2 = 2
Value of x + y = 2
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