What's wrong with this? (basic algebra)

[Robert'); DROP TABLE *;]

I was suspecting the completing the square step, but that checks out, and I can't see any other sneakiness.

[t1mm01994]

it's the part where they take the square root of both sides. 4-9/2 = -1/2, and 5-9/2 = 1/2. -(1/2)^2 = (1/2)^2, but -.5 != .5

[gorcee]

it's the part where they take the square root of both sides. 4-9/2 = -1/2, and 5-9/2 = 1/2. -(1/2)^2 = (1/2)^2, but -.5 != .5

Slight typo there. Should read (-1/2)^2 = (1/2)^2

[Xanthir]

Sigh. The answer is *always* "the part where they take the square root of both sides".

[t1mm01994]

nah, I know several from the type "the part where they divide by 0".. Or with a > rather than a = in which the clue is "the part where they divide by a negative number".