How do you solve the system 5x+5y= -105x+5y=10 and -4x+2y= -104x+2y=10?

1 Answer
Mar 21, 2018

See a solution process below:

Explanation:

Step 1) Solve the first equation for xx:

5x + 5y = -105x+5y=10

(5x + 5y)/color(red)(5) = -10/color(red)(5)5x+5y5=105

(5x)/color(red)(5) + (5y)/color(red)(5) = -25x5+5y5=2

x + y = -2x+y=2

x + y - color(red)(y) = -2 - color(red)(y)x+yy=2y

x + 0 = -2 - yx+0=2y

x = -2 - yx=2y

Step 2) Substitute (-2 - y)(2y) for xx in the second equation and solve for yy:

-4x + 2y = -104x+2y=10 becomes:

-4(-2 - y) + 2y = -104(2y)+2y=10

(-4 xx -2) + (-4 xx -y) + 2y = -10(4×2)+(4×y)+2y=10

8 + 4y + 2y = -108+4y+2y=10

8 + (4 + 2)y = -108+(4+2)y=10

8 + 6y = -108+6y=10

8 - color(red)(8) + 6y = -10 - color(red)(8)88+6y=108

0 + 6y = -180+6y=18

6y = -186y=18

(6y)/color(red)(6) = -18/color(red)(6)6y6=186

(color(red)(cancel(color(black)(6)))y)/cancel(color(red)(6)) = -3

y = -3

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

x = -2 - y becomes:

x = -2 - (-3)

x = -2 + 3

x = 1

The Solution Is:

x = 1 and y = -3

Or

(1, -3)