Problem to solve
Solve \[-\frac{2}{3}x+5y=4\], \[7x-5y=4\]
Solution
STEP 1
Solve the following system:
{5 y - (2 x)/3 = 4
-5 y + 7 x = 4
STEP 2
Express the system in matrix form:
(-2/3 | 5
7 | -5)(x
y) = (4
4)
STEP 3
Solve the system with Cramer's rule:
x = 4 | 5
4 | -5/-2/3 | 5
7 | -5 and y = (-2/3 | 4
7 | 4)/(-2/3 | 5
7 | -5)
STEP 4
Evaluate the determinant -2/3 | 5
7 | -5 = (-95)/3:
x = 4 | 5
4 | -5/(-95/3) and y = (-2/3 | 4
7 | 4)/(-95/3)
STEP 5
The gcd of 4 | 5
4 | -5 and -95/3 is 1/3, so 4 | 5
4 | -5/((-95)/3) = (3 4 | 5
4 | -5)/(3 ((-95)/3)) = -3/95 4 | 5
4 | -5:
x = -3/95 4 | 5
4 | -5 and y = (-2/3 | 4
7 | 4)/((-95)/3)
STEP 6
The gcd of -2/3 | 4
7 | 4 and -95/3 is 1/3, so (-2/3 | 4
7 | 4)/((-95)/3) = (3 -2/3 | 4
7 | 4)/(3 ((-95)/3)) = -3/95 -2/3 | 4
7 | 4:
x = (-3 4 | 5
4 | -5)/95 and y = -3/95 -2/3 | 4
7 | 4
STEP 7
Evaluate the determinant 4 | 5
4 | -5 = -40:
x = (-3)/95×-40 and y = (-3 -2/3 | 4
7 | 4)/95
STEP 8
(-3)/95 (-40) = 24/19:
x = 24/19 and y = (-3 -2/3 | 4
7 | 4)/95
STEP 9
Evaluate the determinant -2/3 | 4
7 | 4 = (-92)/3:
x = 24/19 and y = (-3)/95×-92/3
STEP 10
(-3)/95×(-92)/3 = 92/95:
Answer: | 
 | x = 24/19 and y = 92/95