SOLUTION: Please help with equation please; Using Cramers rule,solve system of equation: {8x+3y=5. And. 4x-3y= 7}

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Question 963864: Please help with equation please; Using Cramers rule,solve system of equation: {8x+3y=5. And. 4x-3y= 7}
Found 2 solutions by Fombitz, rothauserc:
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
A=%28matrix%282%2C2%2C8%2C3%2C4%2C-3%29%29
abs%28A%29=-36
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A%5Bx%5D=%28matrix%282%2C2%2C5%2C3%2C7%2C-3%29%29
abs%28A%5Bx%5D%29=-36
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A%5By%5D=%28matrix%282%2C2%2C8%2C5%2C4%2C7%29%29
abs%28A%5By%5D%29=36
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x=abs%28A%5Bx%5D%29%2Fabs%28A%29=-36%2F%28-36%29=1
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y=abs%28A%5By%5D%29%2Fabs%28A%29=36%2F%28-36%29=-1

Answer by rothauserc(4718) About Me  (Show Source):
You can put this solution on YOUR website!
{8x+3y=5. And. 4x-3y= 7}
Let D be the determinant with all the variables, Dx be the determinant for x and Dy be the determinant for y, then
D = matrix(row 1 is 8 3, row 2 is 4 -3) = -24 -12 = -36
Dx = matrix(row 1 is 5 3, row 2 is 7 -3) = -15 -21 = -36
Dy = matrix(row 1 is 8 5, row 2 is 4 7) = 56 -20 = 36
x = Dx / D = -36 / -36 = 1
y = Dy / D = 36 / -36 = -1
therefore,
x = 1, y = -1
check the answer by substituting for x and y in the given equations
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8(1) +3(-1) = 5
8 -3 = 5
5 = 5
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4(1) -3(-1) = 7
4 +3 = 7
7 = 7
our answer checks