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Solve the system of linear equations by elimination
x+y=7
5x+2y=8

2 Answers

4 votes

Answer:

x+y=7

5x+2y=8

-5{x+y=7}

{5x+2y=8

-5x-5y= -35

5x+2y=8

-3y= -27

y= 9

The value of x is

x+y=7

x+9=7

x= -2

User Burke Holland
by
7.8k points
6 votes

Answer:

(- 2, 9 )

Explanation:

x + y = 7 → (1)

5x + 2y = 8 → (2)

multiplying (1) by - 2 and adding to (2) will eliminate y

- 2x - 2y = - 14 → (3)

add (2) and (3) term by term to eliminate y

3x + 0 = - 6

3x = - 6 ( divide both sides by 3 )

x = - 2

substitute x = - 2 into either of the 2 equations and solve for y

substituting into (1)

- 2 + y = 7 ( add 2 to both sides )

y = 9

solution is (- 2, 9 )

User GrizzlyBear
by
7.5k points