What positive number is twice it's own square

 The positive number is  

Step-by-step explanation:  We are given to find the positive number that is twice it's own square.

Let x denotes the required number.

Then, according to the given information, we have

Sine 0 is not considered as a positive number, so the required positive number is

Thus, the positive number is

to find the perimeter of the rectangle this is the expression:

x-9+x-9+3x-4+3x-4=138

if we simplify it:

8x-26=138

remember, 138 is what it all adds up to

the length is 11.5cm

the width is 57.5cm

the area is 661.25cm^2

the answers might not be correct use at own risk