Question

solve. 2(a-1)^2-1=31

Answer 1

add one to both sides, get
\[2(a-1)^2=32\]
divide by 2, get \[(a-1)^2=16\]
take the square root get
\[a-1=4\] or
\[a-1=-4\] add 1 get
\[a=5\] or \[a=-3\]