Answer:

Step-by-step explanation:
Hello!
We can use the difference of square method.
<h2>Difference Of Squares (DOS)</h2>
The formula for the DOS is 
It is a simple way to factor polynomials.
The criteria:
- Has to begin and end with a perfect square
- The operation has to be subtraction
<h3>Factor:</h3>
Begins with a perfect square (x² * x²) and ends with a perfect square (4 * 4)
Warning! Watch out, there may be another DOS!
is another DOS
The x² + 4 is not a DOS because the operation is addition.
The final factored form is 
Step-by-step explanation:
This is the correct answer.
Even according to calculator and working.
So not quite sure why those options are incorrect?
Answer:
I think right answer is integers
They are right except for 12. i think it is C but i could be wrong.
Answer:
cos(x) = square root 2 over 2; tan(x) = 1
Step-by-step explanation:

was, before it was rationalized,

Therefore,

The side opposite the reference angle measures 1, the hypotenuse measures square root 2. That makes the reference angle a 45 degree angle. From there we can determine that the side adjacent to the reference angle also has a measure of 1. Therefore,
and
since tangent is side opposite (1) over side adjacent (1),
tan(x) = 1