Help on quadratic equations!
Solve 3x^2 + 18x + 15 = 0 by completing the square.

3(x + 3)2 = 6; x = −3 + sqrt2, x = −3 − sqrt2
3(x + 9)2 = 12; x = −11, x = −7
3(x + 3)2 = 12; x = −5, x = −1
3(x + 9)2 = 228; x = −9 + sqrt 76, x = −9 − sqrt 76

Question

Help on quadratic equations!
Solve 3x^2 + 18x + 15 = 0 by completing the square. 
 		
	3(x + 3)2 = 6; x = −3 + sqrt2, x = −3 − sqrt2
	3(x + 9)2 = 12; x = −11, x = −7
	3(x + 3)2 = 12; x = −5, x = −1
	3(x + 9)2 = 228; x = −9 + sqrt 76, x = −9 − sqrt 76

iwillrektyou · Answer

I did it, but I got something wrong. Here is my work:

misty1212 · Answer

HI!!

pooja195 · Answer

Find the GCF of all 3 numbers first.

misty1212 · Answer

divide by 3 first

iwillrektyou · Answer

3x^2 + 18x + 15 = 0
(3x^2 + 18x) + 15 = 0
3(x^2 + 6x) + 15 = 0
3(x^2 + 6x + 9) + 15 = 0
Then, to make it equal:
3(x^2 + 6x + 9) + 15 - 3(9) = 0
3(x^2 + 6x + 9) -12 = 0
3(x+3)^2 - 12 = 0
               +12  +12
3(x+3) = 12
Divide 3 on both sides -->
x + 3 = 4