Question 150433
Let's make "x" = side of the orginal square.
Since the {{{Area}}} is given when the sides are lengthened by 7cm, we'll use this condition in solving for "x". So the sides will be {{{x+7}}}, and going to our formula for {{{Area}}} of square,
{{{A=(sides)^2}}}
{{{A=(x+7)^2}}} ---------> {{{121cm^2=x^2+14x+49}}}
{{{x^2+14x-72=0}}} ------> {{{(x+18)(x-4)=0}}}
2 values,
{{{x=-18}}}, don't use since "negative"
{{{x=4cm}}}, USE THIS ONE = ORIGINAL LENGTH
It just makes sense to have this length. Why?
Simply, {{{A=(new sides)^2}}}
{{{121cm^2= (4+7)^2}}}
{{{121cm^2=121cm^2}}}
Thank you,
Jojo