How do you solve y=x-4y=x4 and y=-x+2y=x+2?

1 Answer
Feb 11, 2017

See the entire solution process below:

Explanation:

Step 1) Because the first equation is already solved for yy, substitute x - 4x4 for yy in the second equation and solve for xx:

y = -x + 2y=x+2 becomes:

x - 4 = -x + 2x4=x+2

x - 4 + color(red)(4) + color(blue)(x) = -x + 2 + color(red)(4) + color(blue)(x)x4+4+x=x+2+4+x

x + color(blue)(x) - 4 + color(red)(4) = -x + color(blue)(x) + 2 + color(red)(4)x+x4+4=x+x+2+4

1x + color(blue)(1x) - 0 = 0 + 61x+1x0=0+6

2x = 62x=6

(2x)/color(red)(2) = 6/color(red)(2)2x2=62

(color(red)(cancel(color(black)(2)))x)/cancel(color(red)(2)) = 3

x = 3

Step 2) Substitute 3 for x in the first equation and calculate y:

y = x - 4 becomes:

y = 3 - 4

y = -1

The solution is: x = 3 and y = -1 or (3, -1)