Problem to solve
Solve \[\frac{x}{3}-\frac{y}{2}+z=2\], \[-x-\frac{y}{3}+2z=3\], \[2x-3y+\frac{z}{3}=-1\]
Solution
STEP 1
Solve the following system:
{x/3 - y/2 + z = 2
-x - y/3 + 2 z = 3
2 x - 3 y + z/3 = -1
STEP 2
Express the system in matrix form:
(1/3 | -1/2 | 1
-1 | -1/3 | 2
2 | -3 | 1/3)(x
y
z) = (2
3
-1)
STEP 3
Solve the system with Cramer's rule:
x = (2 | -1/2 | 1
3 | -1/3 | 2
-1 | -3 | 1/3)/(1/3 | -1/2 | 1
-1 | -1/3 | 2
2 | -3 | 1/3) and y = (1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3)/(1/3 | -1/2 | 1
-1 | -1/3 | 2
2 | -3 | 1/3) and z = (1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1)/(1/3 | -1/2 | 1
-1 | -1/3 | 2
2 | -3 | 1/3)
STEP 4
Evaluate the determinant 1/3 | -1/2 | 1
-1 | -1/3 | 2
2 | -3 | 1/3 = 187/54:
x = (2 | -1/2 | 1
3 | -1/3 | 2
-1 | -3 | 1/3)/(187/54) and y = (1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3)/(187/54) and z = (1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1)/(187/54)
STEP 5
The gcd of 2 | -1/2 | 1
3 | -1/3 | 2
-1 | -3 | 1/3 and 187/54 is 1/54, so (2 | -1/2 | 1
3 | -1/3 | 2
-1 | -3 | 1/3)/(187/54) = (54 2 | -1/2 | 1
3 | -1/3 | 2
-1 | -3 | 1/3)/(54×187/54) = 54/187 2 | -1/2 | 1
3 | -1/3 | 2
-1 | -3 | 1/3:
x = 54/187 2 | -1/2 | 1
3 | -1/3 | 2
-1 | -3 | 1/3 and y = (1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3)/(187/54) and z = (1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1)/(187/54)
STEP 6
The gcd of 1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3 and 187/54 is 1/54, so (1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3)/(187/54) = (54 1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3)/(54×187/54) = 54/187 1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3:
x = (54 2 | -1/2 | 1
3 | -1/3 | 2
-1 | -3 | 1/3)/187 and y = 54/187 1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3 and z = (1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1)/(187/54)
STEP 7
The gcd of 1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1 and 187/54 is 1/54, so (1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1)/(187/54) = (54 1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1)/(54×187/54) = 54/187 1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1:
x = (54 2 | -1/2 | 1
3 | -1/3 | 2
-1 | -3 | 1/3)/187 and y = (54 1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3)/187 and z = 54/187 1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1
STEP 8
Evaluate the determinant 2 | -1/2 | 1
3 | -1/3 | 2
-1 | -3 | 1/3 = 71/18:
x = 54/187×71/18 and y = (54 1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3)/187 and z = (54 1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1)/187
STEP 9
54/187×71/18 = 213/187:
x = 213/187 and y = (54 1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3)/187 and z = (54 1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1)/187
STEP 10
Evaluate the determinant 1/3 | 2 | 1
-1 | 3 | 2
2 | -1 | 1/3 = 14/3:
x = 213/187 and y = 54/187×14/3 and z = (54 1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1)/187
STEP 11
54/187×14/3 = 252/187:
x = 213/187 and y = 252/187 and z = (54 1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1)/187
STEP 12
Evaluate the determinant 1/3 | -1/2 | 2
-1 | -1/3 | 3
2 | -3 | -1 = 143/18:
x = 213/187 and y = 252/187 and z = 54/187×143/18
STEP 13
54/187×143/18 = 39/17:
Answer: | 
 | x = 213/187 and y = 252/187 and z = 39/17