How do you solve the following system: 3x - 2y = 9, 2x + 3y = 12?

2 Answers
May 16, 2017

Arrange your equation and get the solution x=51/13 and y=18/13

Explanation:

9x-6y=27
4x-6y=24

when you expand the first equation (3) and the second (2)
Combine the above equations:

9x+4x=51
x=51/13

Put this value in any equation to get y

2*51/13 + 3y=12

3y=(156-102)/13

y=54/(13*3)

y=18/13

Your x=51/13 and your y=18/13

May 16, 2017

See a solution process below:

Explanation:

Step 1) Solve the first equation for x:

3x - 2y = 9

3x - 2y + color(red)(2y) = 9 + color(red)(2y)

3x - 0 = 9 + 2y

3x = 9 + 2y

(3x)/color(red)(3) = (9 + 2y)/color(red)(3)

(color(red)(cancel(color(black)(3)))x)/cancel(color(red)(3)) = 9/3 + (2y)/3

x = 3 + 2/3y

Step 2) Substitute 3 + 2/3y for x in the second equation and solve for y:

2x + 3y = 12 becomes:

2(3 + 2/3y) + 3y = 12

(2 * 3) + (2 * 2/3y) + 3y = 12

6 + 4/3y + 3y = 12

6 + 4/3y + (3/3 * 3y) = 12

6 + 4/3y + 9/3y = 12

6 + 13/3y = 12

-color(red)(6) + 6 + 13/3y = -color(red)(6) + 12

0 + 13/3y = 6

13/3y = 6

color(red)(3)/color(blue)(13) xx 13/3y = color(red)(3)/color(blue)(13) xx 6

cancel(color(red)(3))/cancel(color(blue)(13)) xx color(blue)(cancel(color(black)(13)))/color(red)(cancel(color(black)(3)))y = 18/13

y = 18/13

Step 3) Substitute 18/13 for y in the solution to the first equation at the end of Step 1 and calculate x:

x = 3 + 2/3y becomes:

x = 3 + (2/3 xx 18/13)

x = 3 + (2/color(red)(cancel(color(black)(3))) xx (color(red)(cancel(color(black)(18)))6)/13)

x = 3 + 12/13

x = (13/13 xx 3) + 12/13

x = 39/13 + 12/13

x = 51/13

The solution is: x = 51/13 and y = 18/13 or (51/13, 18/131)