How do solve the following linear system?: 5x-5y=10 , -4x-14y=28 5x5y=10,4x14y=28?

1 Answer
Feb 9, 2017

See the entire solution process below:

Explanation:

Step 1) Solve the first equation for xx:

5x - 5y = 105x5y=10

5x - 5y + color(red)(5y) = 10 + color(red)(5y)5x5y+5y=10+5y

5x - 0 = 10 + 5y5x0=10+5y

5x = 10 + 5y5x=10+5y

(5x)/color(red)(5) = (10 + 5y)/color(red)(5)5x5=10+5y5

(color(red)(cancel(color(black)(5)))x)/cancel(color(red)(5)) = 10/color(red)(5) + (5y)/color(red)(5)

x = 2 + y

Step 2) Substitute 2 + y for x in the second equation and solve for y:

-4x - 14y = 28 becomes:

-4(2 + y) - 14y = 28

-8 - 4y - 14y = 28

color(red)(8) - 8 - (4 + 14)y = color(red)(8) + 28

0 - 18y= 36

-18y = 36

(-18y)/color(red)(-18) = 36/color(red)(-18)

(color(red)(cancel(color(black)(-18)))y)/cancel(color(red)(-18)) = -2

y = -2

Step 3) Substitute -2 for y in the solution to the first equation at the end of Step 1 and calculate x:

x = 2 + y becomes:

x = 2 + (-2)

x = 0

The solution is: x = 0 and y = -2