# Thread: Wheres this minus come from? :(

1. ## Wheres this minus come from? :(

Completing this square here guys!

5x
² + 5x + 11

Heres how i went through it;

5[x² + x] + 11
5[(x
+ 1/2)² - 1/4] + 11
5(x + 1/2)
² - 5/4 + 11
5(x + 1/2)
² + 39/4

but my book is giving me the answer of

5(x - 1/2)² + 39/4

and i really can't figure out why. probably something stupidly small, that i've missed, but i can't see it!

thanks for any help!
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2. I honestly have no idea, I can only assume that it is a typing error in the book.