how to complete the square x^2+9x=-14

Question

solomonzelman · Answer

$$x^2+9x+20.25=-14+20.25$$

anonymous · Answer

why 20.25?

ddcamp · Answer

$$20.25=(\frac{ 9 }{ 2 })^2$$

solomonzelman · Answer

$$x^2+9x+20.25=6.25$$$$(x+4.5)^2=6.25$$$$(x+4.5)=±~2.5$$$$x=-4.5±~2.5$$

Why 20.25 because 4.5^2 or the last term when you would expand the parenthesis.

anonymous · Answer

i dont understand how to get the 20.25.... or the 9/2 ^2

solomonzelman · Answer

$$x^2+9x=-14$$what do you add to both sides to make it a perfect square?

solomonzelman · Answer

you should get $$(x+4.5)^2$$becuase the middle term is then going to be 9 and the first term x^2, but 
however the last term would be 4.5^2  or  20.25, so this is the number -   20.25 that you should add to both sides, because it's the number that makes the left side into a perfect square.