How do you solve the following system: 6x+2y=-4, x-5y=-96x+2y=4,x5y=9?

1 Answer
Jun 22, 2018

See a solution process below:

Explanation:

Step 1) Solve the second equation for xx:

x - 5y = -9x5y=9

x - 5y + color(red)(5y) = -9 + color(red)(5y)x5y+5y=9+5y

x - 0 = -9 + 5yx0=9+5y

x = -9 + 5yx=9+5y

Step 2) Substitute (-9 + 5y)(9+5y) for xx in the first equation and solve for yy:

6x + 2y = -46x+2y=4 becomes:

6(-9 + 5y) + 2y = -46(9+5y)+2y=4

(6 xx -9) + (6 xx 5y) + 2y = -4(6×9)+(6×5y)+2y=4

-54 + 30y + 2y = -454+30y+2y=4

-54 + (30 + 2)y = -454+(30+2)y=4

-54 + 32y = -454+32y=4

-54 + color(red)(54) + 32y = -4 + color(red)(54)54+54+32y=4+54

0 + 32y = 500+32y=50

32y = 5032y=50

(32y)/color(red)(32) = 50/color(red)(32)32y32=5032

(color(red)(cancel(color(black)(32)))y)/cancel(color(red)(32)) = 25/16

y = 25/16

Step 3) Substitute 25/16 for y in the solution to the second equation at the end of Step 1 and calculate x:

x = -9 + 5y becomes:

x = -9 + (5 xx 25/16)

x = (16/16 xx -9) + 125/16

x = -144/16 + 125/16

x = -19/16

The Solution Is:

x = -19/16 and y = 25/16

Or

(-19/16, 25/16)