Complete the square on:

x^2 - 8k

and

k^2 + 4k

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- March 9th 2008, 11:56 PMstellina_91Complete the square
Complete the square on:

x^2 - 8k

and

k^2 + 4k - March 10th 2008, 12:01 AMMoo
Hello,

Isn't it k^2 - 8k in the first one ?

You must associate these expressions with the formulas you should know :

(a-b)² = a² - 2ab + b²

(a+b)² = a² + 2ab + b²

So in each case, you'll got to find what is a. Then find 2ab. Hence, you got b, and you complete your expressions with b² ;) - March 10th 2008, 04:59 AMtopsquark
Let's demonstrate with the first one:

We are comparing this to

So by matching the coefficients of the linear (k) term we see that

Thus we need to add to the expression. But we can't do that and not change the expression. So we have to be a bit clever about this and add to the expression. That way the value of the expression does not change.

So

You do the second one.

-Dan