SOLUTION: Solve using Cramer's Rule. -2x + 3y = 16 4x = -3y + 40

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Question 47337: Solve using Cramer's Rule.
-2x + 3y = 16
4x = -3y + 40
Answer by longjonsilver(2297) About Me  (Show Source):
You can put this solution on YOUR website!
-2x + 3y = 16
4x = -3y + 40

becomes
-2x + 3y = 16
4x + 3y = 40

in matrix form, we have:

+matrix%282%2C2%2C%0D%0A-2%2C+3%2C%0D%0A4%2C+3%29+

And its determinant is (-2)(3) - (4)(3)
D = -6 - 12
D = -18

Now re-write the matrix as: +matrix%282%2C2%2C%0D%0A16%2C+3%2C%0D%0A40%2C+3%29+

to calculate the x-version Determinant, Dx --> (16)(3) - (40)(3)
Dx = 48 - 120
Dx = - 72

Now re-write the matrix as: +matrix%282%2C2%2C%0D%0A-2%2C+16%2C%0D%0A4%2C+40%29+

to calculate the y-version Determinant, Dy --> (-2)(40) - (16)(4)
Dy = -80 - 64
Dy = -144

Now, x = Dx/D
x = -72/-18
x = 4
and y = Dy/D
y = -144/-18
y = 8

check:
-2x + 3y = 16
-2(4) + 3(8)
-8 + 24
16 --> correct

4x + 3y = 40
4(4) + 3(8)
16 + 24
40 --> correct

Look at my Lesson on a 3x3 Matrix using Cramer's Rule

jon.