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How to write an equation?

Every floor of a building must be conneceted to the basement by a wire. Each floor gets its own indivigual wire. Given any constant hight between floors (h), and x number of floors (f), how do I write an equation that will give me the proper ammount of wire? Thanks!

 Aug 10, 2015

Best Answer 

 #1
avatar+118587 
+5

Hi Parke,

Welcome to the forum :)

 

The first wire is h long, the second is 2h long    the last one is f h long

h, 2h, 3h, .......  f h

 

This is an arithmetic progression.  The first term is h, the common diff is h  the last term is f h

The sum of all these terms is given by the forumula

 

$$s_n=\frac{n}{2}(a+L)$$          n=f,     a=h,    L=f h

 

$$\\S_f=\frac{f}{2}(h+f*h)\\\\
S_f=\frac{f*h}{2}*(1+f)\\\\$$

 Aug 11, 2015
 #1
avatar+118587 
+5
Best Answer

Hi Parke,

Welcome to the forum :)

 

The first wire is h long, the second is 2h long    the last one is f h long

h, 2h, 3h, .......  f h

 

This is an arithmetic progression.  The first term is h, the common diff is h  the last term is f h

The sum of all these terms is given by the forumula

 

$$s_n=\frac{n}{2}(a+L)$$          n=f,     a=h,    L=f h

 

$$\\S_f=\frac{f}{2}(h+f*h)\\\\
S_f=\frac{f*h}{2}*(1+f)\\\\$$

Melody Aug 11, 2015

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