4x-y=9 and 5x+3y=7

Question

find x and y.

Answer 1

Elimination method

Given equations 4x-y = 9 ---> (1)

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

Multiple to each side of equation by 3.

12x-3y = 27 ---> (3)

To eliminate the y value add the equations (3)&(2).

5x+3y = 7

12x-3y = 27

___________

17x = 34

Divide to each side by 17.

17x/17 = 34/17

x = 2

Substitute the x value in (1).

8-y = 9

Subtract 8 from each side.

8-8-y = 9-8

-y = 1

Multiple to each side by negitive one.

y = -1.

Solution x = 2. y = -1.