Answer :
{2x+3y=1
{y=3x+15
2x+3(3x+15)=1
2x+9x+45=1
11x=-44
x=-4
y=3*(-4)+15
y=-12+15=3
y=3
The answer (-4; 3)
2x + 3y = 1
y = 3x + 15
Get the same variables on each side
3y = 1 - 2x
y = 15 + 3x
Multiply both sides of that second equation by 3 so we can subtract.
3y = 1 - 2x
3y = 45 + 9x
Subtract the equations from each other.
0 = -44 - 11x
Solve.
44 = -11x
-4 = x
Use x in an earlier equation to find y.
y = 3x + 15
y = 3 * -4 +15
y = -12 + 15
y = 3
x = -4, y = 3
y = 3x + 15
Get the same variables on each side
3y = 1 - 2x
y = 15 + 3x
Multiply both sides of that second equation by 3 so we can subtract.
3y = 1 - 2x
3y = 45 + 9x
Subtract the equations from each other.
0 = -44 - 11x
Solve.
44 = -11x
-4 = x
Use x in an earlier equation to find y.
y = 3x + 15
y = 3 * -4 +15
y = -12 + 15
y = 3
x = -4, y = 3
