Which relation is the factored form of f(x)=x^2-4x=4

Question

a) f(x)=(x-2)^2

b) f(x)=(x+4)(x-1)

c)f(x)=4(x-1)^2

d)f(x)=(x-2)(x+2)

Answer 1

x^2 - 4x = -4

x^2 -4x +4 = 0

(x-2)^2 = 0

a) would be correct if that 4 on the right side had just been -4 instead of )4

b) is close but not close enough. (x-4)(x+1) = x^2 -3x -4 That's correct except for the -3x.

c) 4(x-1)^2 = 4(x^2 -2x +1) = 4x^2 - 8x +4. Each term is incorrect

d) (x-2)(x+2) = x^2 -4. That's got 2 terms right, but it's missing the 4x middle linear term.

None of the choices are correct

IF this were one of those time pressure standardized tests where they grade it by computer, the "best" answer would probably be a). It has the least chance of getting marked wrong.