The problem asks us to solve two systems of linear equations without graphing. System a: $-5x + 3y = -8$ $3x - 7y = -3$ System b: $-8x - 2y = 24$ $5x - 3y = 2$

AlgebraLinear EquationsSystems of EquationsSubstitutionElimination
2025/4/4

1. Problem Description

The problem asks us to solve two systems of linear equations without graphing.
System a:
5x+3y=8-5x + 3y = -8
3x7y=33x - 7y = -3
System b:
8x2y=24-8x - 2y = 24
5x3y=25x - 3y = 2

2. Solution Steps

System a:
5x+3y=8-5x + 3y = -8 (1)
3x7y=33x - 7y = -3 (2)
Multiply equation (1) by 3 and equation (2) by 5:
3(5x+3y)=3(8)3(-5x + 3y) = 3(-8)
5(3x7y)=5(3)5(3x - 7y) = 5(-3)
15x+9y=24-15x + 9y = -24 (3)
15x35y=1515x - 35y = -15 (4)
Add equation (3) and equation (4):
(15x+9y)+(15x35y)=24+(15)(-15x + 9y) + (15x - 35y) = -24 + (-15)
26y=39-26y = -39
y=3926=32y = \frac{-39}{-26} = \frac{3}{2}
Substitute y=32y = \frac{3}{2} into equation (1):
5x+3(32)=8-5x + 3(\frac{3}{2}) = -8
5x+92=8-5x + \frac{9}{2} = -8
5x=892=16292=252-5x = -8 - \frac{9}{2} = -\frac{16}{2} - \frac{9}{2} = -\frac{25}{2}
x=2525=2510=52x = \frac{-\frac{25}{2}}{-5} = \frac{25}{10} = \frac{5}{2}
System b:
8x2y=24-8x - 2y = 24 (1)
5x3y=25x - 3y = 2 (2)
Multiply equation (1) by -3 and equation (2) by -2:
3(8x2y)=3(24)-3(-8x - 2y) = -3(24)
2(5x3y)=2(2)-2(5x - 3y) = -2(2)
24x+6y=7224x + 6y = -72 (3)
10x+6y=4-10x + 6y = -4 (4)
Subtract equation (4) from equation (3):
(24x+6y)(10x+6y)=72(4)(24x + 6y) - (-10x + 6y) = -72 - (-4)
24x+6y+10x6y=72+424x + 6y + 10x - 6y = -72 + 4
34x=6834x = -68
x=6834=2x = \frac{-68}{34} = -2
Substitute x=2x = -2 into equation (1):
8(2)2y=24-8(-2) - 2y = 24
162y=2416 - 2y = 24
2y=2416=8-2y = 24 - 16 = 8
y=82=4y = \frac{8}{-2} = -4

3. Final Answer

System a: x=52,y=32x = \frac{5}{2}, y = \frac{3}{2}
System b: x=2,y=4x = -2, y = -4

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