The left 8 represents 8000 units.
The right 8 represents 8 units.
Their placement in the number is used to signify the multiplier for the number of units they represent. That is why the number system is called a "place value number system." Each time the digit is moved left one place, its value increases by a factor of 10.
Rational number, because the Square root of 400 is 20, since 20 x itself is 400. Hope this helps!
Your question is a little ambiguous, but I am assuming that you meant to say the function 
Thus, I am solving your question based on assuming the function such as

But, it would still clear your concept, no matter what the function is.
Answer:
we conclude that

The graph is also attached.
Step-by-step explanation:
Given the function

We know that the domain of a function is the set of input or argument values for which the function is real and defined.
As the function has no undefined points nor domain constraints.
Thus, the domain is

Therefore, we conclude that

The graph is also attached.
This is the isosceles right triangle, the diagonal of a square, the thing that so upset the Pythagoreans. The two sides and diagonal of a square are in ratio
so we get

We could have also gotten this using Trig:


Or by recognizing u=v because remaining angle is 45 so this must be isosceles so


