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Mathematics 20 Online
OpenStudy (anonymous):

i think the answer is 121? not sure how to answer this will post screenshot

OpenStudy (anonymous):

zepdrix (zepdrix):

121? hehe that seems way too large :D

zepdrix (zepdrix):

So like..

zepdrix (zepdrix):

\[\large\rm y=x^2+bx\]To complete the square, Toby adds 121 to each side,\[\large\rm y+121=x^2+bx+121\]

zepdrix (zepdrix):

121 is a perfect square, do you know which one? :) Hint 12*12 = 144 9*9 = 81 it's somewhere between there, ya?

OpenStudy (anonymous):

9?

OpenStudy (anonymous):

so thats the coefficent?

OpenStudy (anonymous):

oh you mean for 121!!

zepdrix (zepdrix):

9*9=81, not 121 0_o

OpenStudy (anonymous):

wait so 9 or11?

zepdrix (zepdrix):

We're not to the answer yet... I'm just asking if you can tell me the square root of 121.

OpenStudy (anonymous):

oh okay that is 11

zepdrix (zepdrix):

Ok good :) Let's rewrite the 121 as 11*11 then.\[\large\rm y+121=x^2+bx+11\cdot11\] When completing the square, we have this squared number on the end, and we have TWO of these x's in the middle. So the completed square should look like this:\[\large\rm x^2+11x+11x+11\cdot11\]

zepdrix (zepdrix):

So what is the coefficient on your x term? :) Combine like-terms first!!

zepdrix (zepdrix):

Or if this easier for you, square root the 121, then double that number. That's how you find the middle coefficient ^^

OpenStudy (anonymous):

x^2+22x+121

OpenStudy (anonymous):

okay so then the coefficent is 22 then

zepdrix (zepdrix):

Yes :) Good job!

OpenStudy (anonymous):

cool thanks

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