Answer:
Let y = f(x) be a function with an independent variable x and a dependent variable y.
If a function f provides a way to successfully produce a single value y using for that purpose a value for x then that
chosen x-value is said to belong to the domain of f. If there is a requirement that a y-value produced by a function
must be a real number, the following conditions are commonly checked:
1. Denominators cannot equal 0.
2. Radicands (expressions under a radical symbol) of even roots (square roots, etc)
cannot have a negative value.
3. Logarithms can only be taken of positive values.
4. In word problems physical or other real-life restrictions might be imposed, e.g. time is
nonnegative, number of items is a nonnegative integer, etc.
Answer: The correct line is

Step-by-step explanation: We are given the following two sets of quadratic expressions in various forms:

We are to select one of the lines from above that represent three equivalent expressions.
We can see that there are three different forms of a quadratic expression in each of the lines:
First one is the simplified form, second is the factorised form and third one is the vertex form.
So, to check which line is correct, we need to calculate the factorised form and the vertex form from the simplified form.
We have

and

So,

Thus, Line 1 contains three equivalent expressions.
Now,

and

So,

Thus, Line 2 does not contain three equivalent expressions.
Hence, Line 1 is correct.
Answer:
C) 30 by 10
Step-by-step explanation:
If the rail is ten meters long, and the rope is 10 meters long, they can travel 10 meters left of the rail, ten meters along the rail, ten meters right of the rail, and ten meters above the rail.