Re: Completing the square

Quote:

Originally Posted by

**Krislton** Right the questions was:

(i) By completing the square, find in terms of k the roots of the equation $\displaystyle x^2 + 2kx -7 = 0 $

That can written as $\displaystyle (x+k)^2=k^2+7.$

Re: Completing the square

Do you know how to multiply polynomials? In particular do you know that $\displaystyle (x+ k)^2= x^2+ 2kx+ k^2$? If so compare that with the your expression:

$\displaystyle x^2+ 2kx+ k^2$ and $\displaystyle x^2+ 2kx- 7$ You need to get $\displaystyle k^2$ and get rid of -7. You can do that by adding [itex]k^2[/itex] and 7 to both sides of the equation.