Completing the square?

Question

Your supposed to solve for x by completing the square. 3x^2+24x+36<0.

thanks.

Answer 1

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3x^2 + 24x < -36

x^2 + 8x < -12

x^2 + 8x + (8/2)^2 < -12 + (8/2)^2

x^2 + 8x + 16 < 4

(x + 4)^2 < 4

x + 4 < ± √4

x + 4 < ± 2

x < -2

x > -6

Answer 2

divide everything by 3.

x^2+8x+12<0

b/2 = 8/2=4

(b/2)^2=16

(x+4)^2<4

x+4<2 or x+4<-2

x<-2 or x<-6

Answer 3

3(x+4)^2 + 36 < 0 + 42

3(x+4)^2 < 6

(x+4)^2 < 2

-5.4 < x < -2.6