Can someone help with these?

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C++

1)S=1*2+2*3+3*4+....+19*20

2)f=1+1/1!+1/2!+...+1/10!

Posted 27-Mar-12 22:45pm

enigma10

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Richard MacCutchan 28-Mar-12 4:51am

They could if you asked a proper question.

2 solutions

Solution 2

Try this: http://www.numberempire.com/seriescalculator.php[^]
Entering the limits 1 to 19 and the formula

n*(n+1)

gives you 2660
Entering the limits 1 to 10 and the formula

1/n!

gives you 6235301/3628800
(ok, you can calculate that fraction with a pocket calculator if you're more comfortable with that, or just take the value OriginalGriff already posted)

Now write a function for each formula that arrives at the same results, given the same inputs. To do that, these functions will need to implement the calculation of the individual terms (e. g. n*(n+1)), and then sum them up to a total.

Give it a try, it's not so hard.

Posted 28-Mar-12 2:37am

Stefan_Lang

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OriginalGriff · Accepted Answer · 2012-03-27T23:09:00

Solution 1

Yes.
S = 2660
f = 2.7182818011463845

Posted 27-Mar-12 23:09pm

OriginalGriff

Comments

enigma10 28-Mar-12 5:18am

yes how it is done in c++ code,so when we press debug to show this S=1*2+2*3+3*4+....+19*20
to our monitor

[no name] 28-Mar-12 5:27am

Homework?

OriginalGriff 28-Mar-12 5:30am

If it isn't, I want his job! I could do it standing on my head and typing with my toes...:laugh:

[no name] 28-Mar-12 5:37am

"I want his job"
He's in management.

OriginalGriff 28-Mar-12 5:41am

Hmm. So, easy coding and more money....

OriginalGriff 28-Mar-12 5:28am

Since this sound like your homework, perhaps you should have a go?
It really isn't complex - the first one is self contained and will take just three lines of code to work out the value. Two if you don't worry about indentation.
Have a go - it's not difficult. Where do you think you need to start?

Stefan_Lang 28-Mar-12 7:45am

Why bother with line count? As long as your editor can cope with it, there is no reason not to write your complex Client-Server Database Report system in just one line ;p Ok, you may need two executables, so two lines :o)

Stefan_Lang 28-Mar-12 8:30am

puts("S=1*2+2*3+3*4+....+19*20");