\(a+b+c=18\)
Thay b = 10, c = -9 vào
\(a+10+\left(-9\right)=18\)
\(\Rightarrow a=17\)
\(2a-3b+c=0\)
\(2a-\left[3.\left(-2\right)\right]+\left(-9\right)=0\)
\(2a-\left(-6\right)=9\)
\(2a+6=9\)
\(2a=3\Rightarrow a=\frac{3}{2}\)
\(3a-b-2c=2\)
\(3a-6-\left[2.\left(-1\right)\right]=2\)
\(3a-6-\left(-2\right)=2\)
\(\Rightarrow3a=6\)
\(\Rightarrow a=2\)
\(12-a+b+5c=-1\)
\(12-a+\left(-7\right)+\left(5.5\right)=-1\)
\(12-a+\left(-7\right)+25=-1\)
\(12-a=-19\)
\(a=12-\left(-19\right)\)
\(a=31\)
\(1-2b+c=3a-0\)
\(1-\left[2.\left(-3\right)\right]+\left(-7\right)=3a\)
\(1-\left(-6\right)+\left(-7\right)=3a\)
\(0=3a\)
\(a=0\)
a) a + 10 - (-9) = 18
a + 10 = 18 + ( -9 )
a + 10 = 9
a = 9 - 10
a = -1
b)2a - 3 . (-2) + ( -9) = 0
2a - ( -6) = 0 - ( -9 )
2a - ( -6) = 0 + 9
2a - ( -6) = 9
2a = 9 + (-6)
2a = 3
a = 3 : 2
a = 3/2
Trl
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