Problem to solve
Solve \[\frac{2x+y}{3}-\frac{2[x+y]}{4}=2\], \[-\frac{2[x-y]}{5}-\frac{x+2y}{2}=-1\]
Solution
STEP 1
Solve the following system:
{1/2 (-y - x) + 1/3 (y + 2 x) = 2
1/2 (-2 y - x) - 2/5 (-y + x) = -1
STEP 2
Express the system in standard form:
{-y/6 + x/6 = 2
-(3 y)/5 - (9 x)/10 = -1
STEP 3
Express the system in matrix form:
(1/6 | -1/6
-9/10 | -3/5)(x
y) = (2
-1)
STEP 4
Solve the system with Cramer's rule:
x = (2 | -1/6
-1 | -3/5)/(1/6 | -1/6
-9/10 | -3/5) and y = (1/6 | 2
-9/10 | -1)/(1/6 | -1/6
-9/10 | -3/5)
STEP 5
Evaluate the determinant 1/6 | -1/6
-9/10 | -3/5 = (-1)/4:
x = (2 | -1/6
-1 | -3/5)/(-1/4) and y = (1/6 | 2
-9/10 | -1)/(-1/4)
STEP 6
Divide 2 | -1/6
-1 | -3/5 by -1/4: (2 | -1/6
-1 | -3/5)/((-1)/4) = (4 2 | -1/6
-1 | -3/5)/(4 ((-1)/4)) = -4 2 | -1/6
-1 | -3/5:
x = -4 2 | -1/6
-1 | -3/5 and y = (1/6 | 2
-9/10 | -1)/((-1)/4)
STEP 7
Divide 1/6 | 2
-9/10 | -1 by -1/4: (1/6 | 2
-9/10 | -1)/((-1)/4) = (4 1/6 | 2
-9/10 | -1)/(4 ((-1)/4)) = -4 1/6 | 2
-9/10 | -1:
x = -4 2 | -1/6
-1 | -3/5 and y = -4 1/6 | 2
-9/10 | -1
STEP 8
Evaluate the determinant 2 | -1/6
-1 | -3/5 = (-41)/30:
x = -4-41/30 and y = -4 1/6 | 2
-9/10 | -1
STEP 9
-4×(-41)/30 = 82/15:
x = 82/15 and y = -4 1/6 | 2
-9/10 | -1
STEP 10
Evaluate the determinant 1/6 | 2
-9/10 | -1 = 49/30:
x = 82/15 and y = -449/30
STEP 11
-4×49/30 = (-98)/15:
Answer: | 
 | x = 82/15 and y = -98/15