Question 865124
{{{L=3w-7}}}
{{{wL=120}}}
-
{{{w(3w-7)=120}}}
{{{3w^2-7w-120=0}}}
Discriminant is {{{(-7)^2+4*3*120=49+12+120=49+1440=1489}}}, a prime number.

-
{{{highlight(w=(7+sqrt(1489))/6)}}}
-
{{{L=3((7+sqrt(1489))/6)-7=((7+sqrt(1489))/2)-14/2=(7-14+sqrt(1489))/2=highlight(-7+(1/2)sqrt(1489))}}}