How do you solve this system of equations: -6x + 6y = - 12;- 10x + 9y = - 176x+6y=12;10x+9y=17?

1 Answer
Apr 18, 2017

See the entire solution process below:

Explanation:

Step 1) Solve the first equation for yy:

-6x + 6y = -126x+6y=12

(-6x + 6y)/color(red)(6) = -12/color(red)(6)6x+6y6=126

(-6x)/color(red)(6) + (6y)/color(red)(6) = -26x6+6y6=2

-x + y = -2x+y=2

color(red)(x) - x + y = color(red)(x) - 2xx+y=x2

0 + y = x - 20+y=x2

y = x - 2y=x2

Step 2) Substitute x - 2x2 for yy in the second equation and solve for xx:

-10x + 9y = -1710x+9y=17 becomes:

-10x + 9(x - 2) = -1710x+9(x2)=17

-10x + (9 * x) - (9 * 2) = -1710x+(9x)(92)=17

-10x + 9x - 18 = -1710x+9x18=17

-x - 18 = -17x18=17

-x - 18 + color(red)(18) = -17 + color(red)(18)x18+18=17+18

-x - 0 = 1x0=1

-x = 1x=1

color(red)(-1) * -x = color(red)(-1) * 11x=11

x = -1x=1

Step 3) Substitute -11 for xx in the solution to the first equation at the end of Step 1 and calculate yy:

y = x - 2y=x2 becomes:

y = -1 - 2y=12

y = -3y=3

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