How do you solve by completing the square 2x^2+4x+12=02x2+4x+12=0?

1 Answer
Gió
Apr 1, 2015

Start by writing:
2x^2+4x=-122x2+4x=−12
x^2+4/2x=-12/2x2+42x=−122
x^2+2x=-6x2+2x=−6
x^2+2x+1-1=-6x2+2x+1−1=−6
(x+1)^2=-6+1(x+1)2=−6+1
(x+1)^2=-5(x+1)2=−5
(x+1)=+-sqrt(-5)(x+1)=±√−5
You have a negative squre root!
Did you see complex numbers yet?
If NOT stop here and say "no real solutions".
If YES:
x=-1+-isqrt(5)x=−1±i√5

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