Question 194530
for 2 variable system:

A1x + B1y = C
A2x + B2y = C

we define:(use this formulas in 2 var. below for solving the determinants first)

D = 

A1   B1
A2   B2


Dx = 

C1   B1
C2   B2


Dy = 

A1   C1
A2   C2

Then: (using cramers rule for final step)

X = DX/D

Y = DY/D

given(2 Variables):

2x - 7y = -4
x  -  y = 3

solution: (just follow the formulas above:)


D = 

2   -7
1   -1


Dx = 

-4   -7
 3   -1


Dy =  

2  -4
1   3

now calculate each of these determinants:

D = 2(-1) - (-7)(1) = -2 + 7 = 5

Dx = (-4)(-1) - 3(-7) = 4 + 21 = 25

Dy = 3(2) - (-4)1 = 6 + 4 = 10

so now i already find each of their determinants... so we can now use the cramers rule......(its very simple by using the formula above)

X = Dx/D = 25/5 = 5

Y = Dy/D = 10/5 = 2

congratulations...!!! youve now already solved the x & y's !!!! Invader Rulezzz!