2021 Fall AMC 12B Problems/Problem 7

Revision as of 22:28, 23 November 2021 by Wilhelmz (talk | contribs) (Solution 1 (Bash))

Solution 1 (Bash)

Just plug in all these options one by one, and one sees that all but $D$ fails to satisfy the equation.

For $D$, substitute $z=x$ and $y=x+1$:

$LHS=x(x-(x+1))+(x+1)(x+1-x)+x(x-x)=(-x)+(x+1)=1=RHS$

Hence the answer is $\boxed{\textbf{(D)}}.$

~Wilhelm Z