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**Lepzed** I'm working through some exercises to brush up my pre-calculus algebra and I'm asked to solve several exercises by completing the square (n.b. using the abc-formula isn't allowed for these exercises).

$\displaystyle x^2 + 7x - 1 = 0$

This kind of puzzles me, again: I can't use the abc-formula. The uneven b (7x) doesn't allow for a square, unless I add an x, which would get me something like: $\displaystyle x^2 + 8x + 16 = x + 17$, which seems an unfruitful endeavor...

Any tips?