Let's begin by listing out the information given to us:
There are four students: n = 4
Number of students to be selected: r = 2
To calculate the combination of 2 students to be chosen, we use:

Therefore, there 12 possible combinations from these
Answer: C: 3600
Step-by-step explanation: When trying to find the area of a rectangle or a square all you need to do is multiply the Length and the Width (L * W). The equation you need to solve this is 80 * 45 = x. The answer is 3600.
Answer:
a) 
b)
c) 
Step-by-step explanation:
a) Let <u>a</u>=<2,1,-3>
The magnitude of <u>a</u> is 

The unit vector in the direction of a is

Using the relation
, we have

b) Let a=2i - 3j + 4k



Using the relation
, we have

c) Let us first find the sum of <1, 2, -3> and <2, 4, 1> to get:
<1+2, 2+4, -3+1>=<3, 6, -2>
Let a=<3, 6, -2>
The magnitude is


The unit vector in the direction of <u>a</u> is

Using the relation
, we have

Answer:
Step-by-step explanation:
This is an order of operations question. First in PEMDOS you want to do your parenthesis, turn (5-2) into 3,
15 ÷ 3 + 4
Then do your divison, turning 15 ÷ 3 into 5
5 + 4
Then finish with 5 + 4
The answer is 9