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# FP1 Standard result for r Watch

1. What's the difference between the result

and the result

2. (Original post by huiop)
What's the difference between the result

and the result

The first one is while the first one .
3. (Original post by B_9710)
The first one is while the first one where there are n b's.
so how would i know which one to use in a question which says

show that

so far i got to this

then i went to this

so that 4n is wrong so how would i know to use standard result for r instead of b?
4. (Original post by huiop)
so how would i know which one to use in a question which says

show that

so far i got to this

then i went to this

so that 4n is wrong so how would i know to use standard result for r instead of b?
Where does the come from?

5. (Original post by RDKGames)
Where does the come from?

whoops typing error i thought i could use x as a substitute for \times
6. (Original post by huiop)
whoops typing error i thought i could use x as a substitute for \times
As for the difference between and ;

If it's r, then you are adding 1+2+3+4+5+...+n because you are summing up the integers from r=1 up to r=n.

If it's a constant (like b), then you are adding b+b+b+b+b+...+n because you are summing up a constant b, in a series of b, b, b, b, b, b, .... where every single term is b. So r=1 will be b, and r=2 will be b, and r=3 and so on up to r=n. Hence where nb comes from. As you are summing b an n amount of times.
7. (Original post by RDKGames)
As for the difference between and ;

If it's r, then you are adding 1+2+3+4+5+...+n because you are summing up the integers from r=1 up to r=n.

If it's a constant (like b), then you are adding b+b+b+b+b+...+n because you are summing up a constant b, in a series of b, b, b, b, b, b, .... where every single term is b. So r=1 will be be, and r=2 will be b, and r=3 and so on up to r=n. Hence where nb comes from. As you are summing b an n amount of times.
ok thanks for clarification
8. (Original post by huiop)
so how would i know which one to use in a question which says

show that

so far i got to this

then i went to this

so that 4n is wrong so how would i know to use standard result for r instead of b?
Think about what this notation means. If you have since there are n 1's. Using this notation, the sum is with respect to only. So if we have not .

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