00:01
Hello students, first question we have given that n -7! divided by n -8! is equal to 15 and we have to solve this question.
00:10
So, now we know the formula for the n! n! is equal to n into n -1! so, by using this formula we can write n -7! as n -7 into n -8! divided by n -8! and that is equal to 15.
00:38
Now n -8! will get cancelled and we have n -7! is equal to 15.
00:46
Therefore, the value of n is equal to 22.
00:52
Then the second question is n plus 5! divided by n plus 3! and that is equal to 72.
01:04
Now n plus 5! we can write it as n plus 5 into n plus 4 into n plus 3! divided by n plus 3! as here and that is equal to 72.
01:21
We have already seen the formula for the n! so by using that formula here i have simplified n plus 5! as this and now this is equal to n plus 5 into n plus 4 is equal to 72.
01:39
So, this is equal to n square plus 13 n minus 4 n minus 52 and that is equal to 0.
01:50
This is the simplification of this and which is equal to n into n plus 13 minus 4 into n plus 13 that is equal to 0...