Question 1082890
If the area of the new square is 121 cm^2, what is x?
-----------------------------------------------------------



x, original square
x+3, the new square


New square area,  {{{(x+3)^2=121}}}
Solve for x.


{{{x^2+6x+9=121}}}

{{{x^2+6x+9-121=0}}}

{{{x^2+6x-112=0}}}, but this should not be necessary.  Square expression is already complete at {{{x^2+6x+9=121}}}  or at {{{(x+3)^2=121}}}.


-
Instead, no need to Complete Square.
Just use  {{{x+3=sqrt(121)=11}}}
{{{x=11-3}}}
{{{x=8}}}