4, 21, 38, common difference
2 answers:
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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.