Answer:
D. y = -x^2 + 1
Step-by-step explanation:
Hello!
The answer for A is:

The answer for B is: The rocket will hit the lake surface in 5 seconds.
<h2>Why?</h2>
Defining the terms:

So, replacing it in the quadratic equation (it's given to you in the exercise)\\



We are working with a quadratic equation, so we will have two possible results,

Now, we are asked to find the time, time can not be a negative value, we have to discard X1 (-1) since it's a negative value, knowing that, the rocket will hit the lake after 5 seconds.
Have a nice day!
A postulate is a true statement that does not require to be proved . Also called an axiom.
Answer:
1
Step-by-step explanation:
Working step by step I first see all my different groups then add them all together
so
12 - cats
15 - dogs
6 - both
9 - neither
12 students + 15 students + 6 students + 9 students = 42 students
therefore 42 students are in the class
16 + 10 + 3 + 12 = 41
I’m sorry if i got it wrong!