Question 114794
Since you sliced off one inch that measurement is now (x-1). 
The other two faces stays at x. 
The volume then equals,
{{{V=x(x)(x-1)=x^3-x^2=294}}}
{{{x^3-x^2-294=0}}}
You can factor that equation.
{{{x^3-x^2-294=(x^2+6x+42)(x-7)=0}}}
The roots for 
{{{x^2+6x+42}}}
are complex, so that leaves
{{{x-7=0}}} 
{{{x=7}}} 
Check your answer
V =7*7*6=294
Good answer.