Question 916227


given:

pen area is {{{A=120x-4x^2}}}... find {{{x}}}

set {{{A=0}}}

{{{0=120x-4x^2}}} ...factor 

{{{0=4x(30-x)}}}

solutions:

if {{{4x=0}}} => {{{x=0}}} ....we don't need that ..:-)

if {{{30-x=0}}} => {{{x=30}}} ....this is solution we need,width will result in the largest possible pen area

so, ..max area will be  

{{{A=x^2}}}... plug in {{{x=30}}}

{{{A=30^2}}} 

{{{A=900}}}