How do you solve the following linear system: -x + y = 3, 5x-2y=11 x+y=3,5x2y=11?

1 Answer
Jun 14, 2018

See a solution process below:

Explanation:

Step 1) Solve the first equation for yy:

-x + y = 3x+y=3

-x + color(red)(x) + y = 3 + color(red)(x)x+x+y=3+x

0 + y = 3 + x0+y=3+x

y = 3 + xy=3+x

Step 2) Substitute (3 + x)(3+x) for yy in the second equation and solve for xx:

5x - 2y = 115x2y=11 becomes:

5x - 2(3 + x) = 115x2(3+x)=11

5x - (2 * 3) - (2 * x) = 115x(23)(2x)=11

5x - 6 - 2x = 115x62x=11

5x - 6 + color(red)(6) - 2x = 11 + color(red)(6)5x6+62x=11+6

5x - 0 - 2x = 175x02x=17

5x - 2x = 175x2x=17

(5 - 2)x = 17(52)x=17

3x = 173x=17

(3x)/color(red)(3) = 17/color(red)(3)3x3=173

(color(red)(cancel(color(black)(3)))x)/cancel(color(red)(3)) = 17/3

x = 17/3

Step 3) Substitute 17/3 for x in the solution to the first equation at the end of Step 1 and calculate y:

y = 3 + x becomes:

y = 3 + 17/3

y = (3/3 * 3) + 17/3

y = 9/3 + 17/3

y = 26/3

The Solution Is:

x = 17/3 and y = 26/3

Or

(17/3, 26/3)