Completing the Square help! (1 Viewer)

[borkis04]

Hey guys!..yeh im revising and came up against something where i thought i knew it..but i actually dont a year later after I learnt it a year ago. Most probably just forgotten but im confused abt general problems with completing the square's.

take this as an example...and express it as (y - k) = (x - b)^2

y = x^2 - 10x + 5

okay i know its a really simple question but here's my working out:

y = x^2 - 10x + 5

y - 5 = x^2 - 10x

y - 5 = (x - 5)^2

y - 5 = (x - 5)^2...???? i dont know how do like complete the square in this line..and im then stuck!

im just confused on what i do next..and how i get to the answer as it says in the textbook as

(y + 20) = (x - 5)^2

Thanks in advance guys!
Any help is much appreciated!

 

[icycloud]

Since you added 25 to the RHS to complete the square, you must add 25 to the LHS as well. Therefore, y - 5 + 25 = y + 20, like the answer says.

 

[borkis04]

Since you added 25 to the RHS to complete the square, you must add 25 to the LHS as well. Therefore, y - 5 + 25 = y + 20, like the answer says.

ohh! thansk mate!
i see now..sweet cheers dood
hav a good 1!