How do you solve by substitution 5x-6y=6 and 5x+y=2?

2 Answers
Apr 29, 2018

y=-4/7
x=18/35

Explanation:

5x-6y=6 --- (1)
5x+y=2 --- (2)

(1) minus (2)

-6y-y=6-2
-7y=4
y=-4/7 --- (3)

Sub (3) into (1)

5x-6times-4/7=6
5x+24/7=6
5x=18/7
x=18/35

Apr 29, 2018

The solution is (18/35,-4/7) or (0.514,-0.571).

Explanation:

Solve the system of equations.

"Equation 1": 5x-6y=6

"Equation 2": 5x+y=2

The solution to the system of linear equations is the point they have in common, the point of intersection. The system will be solved using substitution.

Solve Equation 2 for y.

y=-5x+2

Substitute -5x+2 for y in Equation 1. Solve for x.

5x-6(-5x+2)=6

Expand.

5x+30x-12=6

Simplify.

35x-12=6

Add 12 to both sides.

35x=6+12

Simplify.

35x=18

Divide both sides by 35.

x=18/35 or 0.514

Substitute 18/35 for x in Equation 2. Solve for y.

5(18/35)+y=2

Simplify color(red)cancel(color(black)(5))^1(18/color(red)cancel(color(black)(35))^7) to 18/7.

18/7+y=2

Multiply both sides by 7.

color(red)cancel(color(black)(7))^1xx18/color(red)cancel(color(black)(7))^1+7xxy=2xx7

Simplify.

18+7y=14

Subtract 18 from both sides.

7y=14-18

Simplify.

7y=-4

Divide both sides by 7.

y=-4/7 or -0.571

Solution

(18/35,-4/7) or (0.514,-0.571)

graph{(y-5/6x+1)(y+5x-2)=0 [-10, 10, -5, 5]}