Question 764149
n and n+1

n(n+1)=n+(n+1)+19


{{{n^2+n=2n+19}}}
{{{n^2=n+19}}}
{{{n^2-n-19=0}}}


{{{n=(1+- sqrt(1+4*19))/2}}}
{{{n=(1+- sqrt(81))/2}}}
{{{n=(1+- 9)/2}}}
{{{n=-4}}} or {{{n=5}}}