Solve x2 + 8x - 48 = 0 by completing the square .

Question

karatechopper · Answer

Show me what you got so far?

anonymous · Answer

what does completing the square mean ?

anonymous · Answer

You need to add a constant to both sides to create a "perfect square trinomial"

anonymous · Answer

sorry, what does that mean ?

anonymous · Answer

?

anonymous · Answer

Like, x^2+2x+1 is a perfect square trinomial, as it can be condensed into (x+1)^2

anonymous · Answer

oh so like factor ?

anonymous · Answer

Sort of, you have to have the correct constant though or it won't work.

anonymous · Answer

(x-4) (x+12) =0

anonymous · Answer

like that ?

anonymous · Answer

That doesn't work. You have to complete the square by adding a constant to each side of the equals sign.

directrix · Answer

x2 + 8x - 48 = 0

x² + 8x = 48

x²  + 8x + _?__   = 48  + __?__

The object is to force the left side of the equation to be a perfect square trinomial.

directrix · Answer

x²  + 8x + _?__   = 48  + __?__

Take half of the coefficient of the linear x term (it is 8) --> 4
Square it.
4²  = 16

x²  + 8x + _16__   = 48  + __16__

directrix · Answer

@koreanhugg    How does x²  + 8x +16 factor?

directrix · Answer

@koreanhugg  is "is offline"

anonymous · Answer

omg sorry ! my internet was being dumb . .

directrix · Answer

Let's pick up where you left off:

@koreanhugg    How does x²  + 8x +16 factor?