Question 211850: solve the equation in the complex number system:
x squared + 12x + 72 = 0
Answer by RAY100(1637)   (Show Source):
You can put this solution on YOUR website! x^2 +12x +72 =0
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use quadratic formula
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a=1,,,b=12,,,,c=72
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x= [-(12) +/- sqrt{(12)^2 - 4 (1)(72)}]/ 2(1)
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x=[-12 +/- sqrt(144 -288}]/2
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x= [-12 +/- sqrt-144}]/2
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x= [ -12 +/- 12i ] /2
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x= -6 +/- 6 i
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check,(-6+6i)^2 +12(-6+6i) +72 =0
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36 -72i +36i^2 -72 +72i +72 =0,,,,,ok
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check for -6-6i will be similar
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