Answer:
A, B and D are true statements.
Step-by-step explanation:
We are given a binomial expansion


Now we will check each option
Option A: The coefficients of
and
both equal 1.
If we see first and last term of the expansion, This statement is true.
Option B: For any term
in the expansion, a + b = n.
Let we take 3rd term of expansion
Here, a=n-2 and b=2
If we do a+b = n-2+2=n
a+b=n is true statement.
Option C: For any term x^ay^b in the expansion, a - b = n.
Let we take 3rd term of expansion
Here, a=n-2 and b=2
If we do a-b = n-2-2=n-4≠n
a-b=n is false statement.
Option D: The coefficients of x^ay^b and x^by^a are equal.
If we take second term from beginning and last of the expansion.


This statement true.
Answer:

Step-by-step explanation:
Given
--- slots
i.e. even numbers between 1 and 34 (inclusive)
Required

The probabiity of winning is the number of even numbers divided by the total slot;
i.e.

So, we have:


The answer is 93
If we sorted out the number of each hours, the sequence will look like this
57 _ 69 _ 81 _ x _ 105
(in which x is the fourth hour of work)
We can see from the sequence that each hours, the mailman add additional 12 letters.
(69 - 57 = 12)
(81 - 69 = 12) . . . . proof
So, the amount of letters on the fourth hour would be:
81 letters + 12 letters = 93 Letters
The answer is x= -21
3x-3=6(x-10)