Question 587907
Here's the plot:
{{{ graph( 400, 400, -12, 5, -20, 5, x^2 + 11x + 10 ) }}}
{{{ x^2 + 11x + 10 }}}
{{{ ( x + 1 )*( x + 10 ) = 0 }}}
{{{ x = -1 }}}
{{{ x = -10 }}}
The difference between the roots is {{{ -1 -(-10) = 9 }}},
so at {{{y=0}}}, which is at ground level, the hole is 9 m wide
and can't be dug