Question 642310
{{{-2x^2 + 300x = 7200 + 60x}}}

{{{-2x^2 + 300x -60x-7200=0 }}}

{{{-2x^2 + 240x -7200=0 }}}.........each term divide by {{{2}}}

{{{-x^2 + 120x -3600=0 }}}....pull minus out of parenthesizes...note: {{{120x}}} you can write as {{{2*60}}} and {{{3600}}} as {{{60^2}}}

so, you have

{{{-(x^2 -2*60x +60^2)=0 }}}...which is squared difference

{{{-(x -60)^2=0 }}}

{{{-(x -60)(x -60)=0 }}}

so, solutions are:{{{-(x -60)=0 }}}...=>...{{{-x +60=0 }}}...=>...{{{60=x }}}

second solution is same

{{{ graph( 600, 600, -10, 85, -40, 20,-x^2 +120x -3600) }}}