Question

The letters ABCDEFGH are to be used to form strings of length four.
How many strings contain the letter A if repetitions are not allowed?

Answer 1

discrete mathematics?

Answer 2

test today? bernardin?

Answer 3

yeah

Answer 4

no

Answer 5

just assignments

Answer 6

Any ideas?

Answer 7

1 sec ill look. done this before but can't remember the exact way to do it

Answer 8

1x7x6x5 =210

Answer 9

ARIED is this the answer you want

Answer 10

that doesn't look right

Answer 11

I did it the long way A _ _ _ C(1,1)*C(7,3)

Answer 12

then _ A _ _

Answer 13

what was your answer?

Answer 14

then _ _ A _ and I got like 840

Answer 15

oh!
it should be 1x7x6x5 x 4 = 840
i did not take combination in consideration

Answer 16

How'd you do it so quick? can you explain

Answer 17

sure