Answer:
Step-by-step explanation:
Given

Required
Which of the above is a quadratic function
A quadratic function has the following form;

So, to get a quadratic function from the list of given options, we simply perform a comparative test of each function with the form of a quadratic function

This is not a quadratic function because it follows the form
and this is different from 
This function has an exact match with 
By comparison; 

This is not a quadratic function because it follows the form
and this is different from 

This is not a quadratic function because it follows the form 
Unlike the quadratic function where 
So, from the list of given options, only
satisfies the given condition
ABout 821.95 hours. 8,425 divided by 10.25 is 821.95
Answer:

Step-by-step explanation:
Let
be the average of the sample, and the population mean will be
We know that:
gr
Let
be the standard deviation and n the sample size, then we know that the standard error of the sample is:

Where


In this case we are looking for:

This is:
or 

Now we get the z score



Looking at the tables for the standard nominal distribution we get


The factors of 4 x² - 9 :
4 x² - 9 = ( 2 x - 3 ) · ( 2 x + 3 )
We have to use the formula for the difference of squares:
a² - b² = ( a - b ) · ( a + b )