Question 769017
x = length
y = width

{{{x=-35+6y}}}
and
area is {{{xy=5379}}}

Find x.


Easiest is find y in terms of x and rewrite the area equation.
{{{x=6y-35 }}}
{{{6y=x+35}}}
{{{y=(x+35)/6}}}, substitute this.


{{{x(x+35)/6=5379}}} , the substitution made into the area equation.
{{{x^2+35x=6*5379}}}
{{{highlight(x^2+35x-6*5379=0)}}}
Use general solution to quadratic formula, use the positive sqrt,
{{{highlight(x=163)}}}