substitution method

Question

 8.  y = 5x                     9.  x = 4y                      10.  x = 4y + 5
    2x + 3y = 34                2x + 3y = 44                       x = 3y - 2

Answer 1

Substitution method

8) Given equations are y = 5x ---> (1)

2x+3y = 34 ---> (2)

From (1) substitute the y value in (2).

2x+3(5x) = 34

2x+15x = 34

17x = 34

Divide to each side by17.

17x/17 = 34/17

x = 2

Substitute the x value in (1).

y = 10

Solution x = 2, y = 10.

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

2x+3y = 44 ---> (2)

From (1) substitute the x value in (2).

2(4y)+3y = 44

8y+3y = 44

11y = 44

Divide to each side by 11.

11y/11 = 44/11

y = 4

Substitutethe y value in (1).

x = 16

Solution x = 16,y = 4.

10) x = 4y+5 ---> (1)

x = 3y-2 ---> (2)

From (2) substitute the x value in (1).

3y-2 = 4y+5

Add 2 to each side.

3y-2+2 = 4y+5+2

3y = 4y+7

Subtract 4y from each side.

3y-4y = 7

-y = 7

Multipleto each side by negitive one.

y = -7.

Substitute the y value in (1).

x = -28+5

x = -23

Solution x = -23, y = -7.