How do you solve the following system?: 2x +y = 6 , x + 3y = -82x+y=6,x+3y=8

1 Answer
Feb 27, 2017

See the entire solution process below:

Explanation:

Step 1) Solve the second equation for xx:

x + 3y = -8x+3y=8

x + 3y - color(red)(3y) = -8 - color(red)(3y)x+3y3y=83y

x + 0 = -8 - 3yx+0=83y

x = -8 - 3yx=83y

Step 2) Substitute -8 - 3y83y for xx in the first equation and solve for yy:

2x + y = 62x+y=6 becomes:

2(-8 - 3y) + y = 62(83y)+y=6

-16 - 6y + y = 6166y+y=6

-16 - 5y = 6165y=6

color(red)(16) - 16 - 5y = color(red)(16) + 616165y=16+6

0 - 5y = 2205y=22

-5y = 225y=22

(-5y)/color(red)(-5) = 22/color(red)(-5)5y5=225

(color(red)(cancel(color(black)(-5)))y)/cancel(color(red)(-5)) = -22/5

y = -22/5

Step 3) Substitute -22/5 for y in the solution to the second equation at the end of Step 1 and calculate x:

x = -8 - 3y becomes:

x = -8 - (3 xx -22/5)

x = -8 - (-66/5)

x = -8 + 66/5

x = (5/5 xx -8) + 66/5

x = -40/5 + 66/5

x = 26/5

The solution is: x = 26/5 and y = -22/5 or (26/5, -22/5)