Completing squares. Lets says I have

x^2 - 4x = 0

To complete the square, I know I do something with -4x. Is it take the square root of 4?

Question

Completing squares. Lets says I have

x^2 - 4x = 0 

To complete the square, I know I do something with -4x. Is it take the square root of 4?

cggurumanjunath · Answer

(x-(4/2))^2=0+(4/2)^2

cggurumanjunath · Answer

(x-2)^2=4

hartnn · Answer

You need to divide the co-efficient of x by 2.
then square it.
Add it on both sides.

aravindg · Answer

You add a term every time. It is is given an (coefficient of x term/2)^2.

compassionate · Answer

-4/2 = -2

Then the square of -2 is -1... Isn't that an imaginary number?

aravindg · Answer

Squiare of -2 is 4 o.o

compassionate · Answer

You can't take roots of negative numbers....

hartnn · Answer

square of -2 is -2 times -2

compassionate · Answer

Oh...

compassionate · Answer

So... 

(x^2 - 4x) + (y^2 + 8y) = -4

I would say... (x^2 - 4x + 4) + (y^2 + 8y + 16) = - 4 + 4 + 16...

aravindg · Answer

Yep.

compassionate · Answer

Then I would say... 

(x - 2)^2 + (y + 4)^2 = 16...

hartnn · Answer

=4^2
yeah, thats an equation of circle with centre 2,-4 and radius = 4

aravindg · Answer

Yes!

compassionate · Answer

Danke schone. Mucho gracias. شكرا.