Answer:
x = -3 , y = 4 , z = 0
Explanation:
Solve the following system:
{x - 3 y + z = -15
2 x + y - z = -2
x + y + 2 z = 1
Hint: | Choose an equation and a variable to solve for.
In the first equation, look to solve for z:
{x - 3 y + z = -15
2 x + y - z = -2
x + y + 2 z = 1
Hint: | Solve for z.
Subtract x - 3 y from both sides:
{z = 3 y + (-x - 15)
2 x + y - z = -2
x + y + 2 z = 1
Hint: | Perform a substitution.
Substitute z = -15 - x + 3 y into the second and third equations:
{z = -15 - x + 3 y
15 + 3 x - 2 y = -2
x + y + 2 (-15 - x + 3 y) = 1
Hint: | Expand the left hand side of the equation x + y + 2 (-15 - x + 3 y) = 1.
x + y + 2 (-15 - x + 3 y) = x + y + (-30 - 2 x + 6 y) = -30 - x + 7 y:
{z = -15 - x + 3 y
15 + 3 x - 2 y = -2
-30 - x + 7 y = 1
Hint: | Choose an equation and a variable to solve for.
In the second equation, look to solve for x:
{z = -15 - x + 3 y
15 + 3 x - 2 y = -2
-30 - x + 7 y = 1
Hint: | Isolate terms with x to the left hand side.
Subtract 15 - 2 y from both sides:
{z = -15 - x + 3 y
3 x = 2 y - 17
-30 - x + 7 y = 1
Hint: | Solve for x.
Divide both sides by 3:
{z = -15 - x + 3 y
x = (2 y)/3 - 17/3
-30 - x + 7 y = 1
Hint: | Perform a substitution.
Substitute x = (2 y)/3 - 17/3 into the third equation:
{z = -15 - x + 3 y
x = (2 y)/3 - 17/3
(19 y)/3 - 73/3 = 1
Hint: | Choose an equation and a variable to solve for.
In the third equation, look to solve for y:
{z = -15 - x + 3 y
x = (2 y)/3 - 17/3
(19 y)/3 - 73/3 = 1
Hint: | Isolate terms with y to the left hand side.
Add 73/3 to both sides:
{z = -15 - x + 3 y
x = (2 y)/3 - 17/3
(19 y)/3 = 76/3
Hint: | Solve for y.
Multiply both sides by 3/19:
{z = -15 - x + 3 y
x = (2 y)/3 - 17/3
y = 4
Hint: | Perform a back substitution.
Substitute y = 4 into the first and second equations:
{z = -x - 3
x = -3
y = 4
Hint: | Perform a back substitution.
Substitute x = -3 into the first equation:
{z = 0
x = -3
y = 4
Hint: | Sort results.
Collect results in alphabetical order:
Answer: {x = -3 , y = 4 , z = 0