jika 3x+2y=4,2x+5y=-1,ax+by=-6,dan ax-by=-2,maka a-b= (a)-4 (b)-1 (c) 0 (d) 1 (e) 4

y= -1, x=2
a=-2, b=2
a-b= -2-2= -4
jawabannya A

3x + 2y = 4 |2| 6x + 4y = 8
2x + 5y = -1 |3| 6x + 15y = -3
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.................................. -11y = 11 => y = -1
3x + 2y = 4 => 3x + 2(-1) = 4 => 3x = 6 => x = 2

ax + by = -6
ax - by = -2
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2ax = -8 => 2a(2) = -8 => a = -2
ax - by = -2 => -2(2) - b(-1) = -2 => -4 + b = -2 => b = 2

a - b = -2 - 2 = -4