please help,
$$14C _{5} + 7!- 17!/3!14!$$
the answer is 6362 but i keep getting a different answer on my calculator

Question

please help,
$$14C _{5} + 7!- 17!/3!14!$$
the answer is 6362 but i keep getting a different answer on my calculator

anonymous · Answer

the 14 should be small like the 5

asnaseer · Answer

ok - lets look at this one term at a time.
what do you get for $_{14}C_5$?

anonymous · Answer

i get 2002

asnaseer · Answer

that is correct.
and 7! ?

anonymous · Answer

i have a ti-84 and i use the nCr

anonymous · Answer

5040

asnaseer · Answer

also correct.
so you must have made a mistake in the last term - what did you get for that?

anonymous · Answer

5.16803703E24

asnaseer · Answer

that is definitely wrong

asnaseer · Answer

$$\frac{17!}{3!14!}=\frac{17*16*15*\cancel{14!}}{3!*\cancel{14!}}=\frac{17*16*15}{3*2}$$

anonymous · Answer

ohh ok i was just putting it straight in my calculator so ill try it like that and let you know if i get it right

asnaseer · Answer

it looks like what you actually calculated was:$$\frac{17!}{3!}\times14!$$

asnaseer · Answer

does your calc have brackets? i.e. can you enter '(' and ')'?

asnaseer · Answer

if it does, then you can try:$$17!\div(3!\times4!)$$

asnaseer · Answer

the 4! should be 14! up there

anonymous · Answer

yes my calculator does. i calculated the whole equation separately but still did not get the answer

asnaseer · Answer

2002 + 5040 - 680 = 6362

anonymous · Answer

i didn't get the 680 i got 2720

asnaseer · Answer

use the brackets as I suggested and recalculate it please

anonymous · Answer

just got it! lol I guess it didn't work before because i did it as 14nCr +7! (17!/3!4!) thank you i got it now!

asnaseer · Answer

you need to be careful with equations like:$$\frac{ab}{cde}$$when using a calculator. always enter this as:$$a\times b\div (c\times d\times e)$$

anonymous · Answer

would i be able to do (ab/(cde))?

asnaseer · Answer

yes - that would also work.

anonymous · Answer

thank you for your help :)

asnaseer · Answer

yw :)

anonymous · Answer

would you happen to know about sequences?

asnaseer · Answer

I do but unfortunately it is very late here and I need to get some sleep now.
Just post it as a new question and I'm sure there will be plenty of other people here willing to help you out.

anonymous · Answer

ohh ok thank you! good night!

asnaseer · Answer

thx - good night!