(7, 3) is the answer I believe
Answer:

Step-by-step explanation:
GIVEN: two two-letter passwords can be formed from the letters A, B, C, D, E, F, G and H.
TO FIND: How many different two two-letter passwords can be formed if no repetition of letters is allowed.
SOLUTION:
Total number of different letters 
for two two-letter passwords
different are required.
Number of ways of selecting
different letters from
letters


Hence there are
different two-letter passwords can be formed using
letters.
Answer:
See below
Step-by-step explanation:

Recall

Using the chain rule

such that 
we can get a general formulation for

Considering the power rule

we have

therefore,

Now, once

we have

Hence, we showed

================================================
For the integration,

considering the previous part, we will use the identity

thus

and

Considering 
and then 
we have

Therefore,


Answer:
Step-by-step explanation: