Cyrus solved a quadratic equation. His work is shown below.
In which step did Cyrus make an error?
\begin{aligned} \dfrac{1}{3}(x-1)^2&=12 (x-1)^2&=36&\text{Step }1 x-1&=6&\text{Step }2 x&=7&\text{Step }3 \end{aligned}
3
1

(x−1)
2

(x−1)
2

x−1
x


=12
=36
=6
=7


Step 1
Step 2
Step 3