How do you solve 3x + 2y = 43x+2y=4 and 2x + y = 32x+y=3?

1 Answer
Mar 17, 2017

See the entire solution process below:

Explanation:

Step 1) Solve the second equation for yy:

2x + y = 32x+y=3

2x + y - color(red)(2x) = 3 - color(red)(2x)2x+y2x=32x

2x - color(red)(2x) + y = 3 - 2x2x2x+y=32x

0 + y = 3 - 2x0+y=32x

y = 3 - 2xy=32x

Step 2) Substitute 3 - 2x32x for yy in the first equation and solve for xx:

3x + 2y = 43x+2y=4 becomes:

3x + 2(3 - 2x) = 43x+2(32x)=4

3x + (2 xx 3) - (2 xx 2x) = 43x+(2×3)(2×2x)=4

3x + 6 - 4x = 43x+64x=4

3x - 4x + 6 = 43x4x+6=4

(3 - 4)x + 6 = 4(34)x+6=4

-1x + 6 = 41x+6=4

-x + 6 - color(red)(6) = 4 - color(red)(6)x+66=46

-x + 0 = -2x+0=2

-x = -2x=2

color(red)(-1) xx -x = color(red)(-1) xx -21×x=1×2

x = 2x=2

Step 3) Substitute 22 for xx in the solution to the second equation at the end of Step 1 and calculate yy:

y = 3 - 2xy=32x becomes:

y = 3 - (2 xx 2)y=3(2×2)

y = 3 - 4y=34

y = -1y=1

The solution is x = 2x=2 and y = -1y=1 or (2, -1)(2,1)