+0  
 
0
158
4
avatar+312 

What is the sum of all the odd integers between 500 and 700?

 Nov 27, 2020
 #1
avatar+129 
0

60000

 Nov 27, 2020
 #2
avatar+115955 
+3

We need to  solve this equation for  n  and then add 1 to the answer to findthe number of terms

 

501 + 2n  =699

 

2n =  699 - 501

 

2n = 198

 

n = 99

 

Number of terms  = 99 + 1   =100

 

Sum =   [ first term + last term ] [ number of terms / 2 ]

 

[ 501 + 699 ]  [ 100/2]  =

 

1200 * 50  =

 

60000

 

 

cool cool cool

 Nov 27, 2020
 #3
avatar+9182 
+2

\(501+503+\dots+697+699\\~\\ =\quad (501+2\cdot0) + (501+2\cdot1) +\dots+(501+2\cdot98) +(501+2\cdot99) \\~\\ =\quad (499+2\cdot1) + (499+2\cdot2) +\dots+(499+2\cdot99) +(499+2\cdot100) \\~\\ =\quad \sum\limits_{n=1}^{100}(499+2n) \\~\\ =\quad \sum\limits_{n=1}^{100}499+ \sum\limits_{n=1}^{100}2n \\~\\ =\quad 100\cdot499+ 2\cdot\sum\limits_{n=1}^{100}n \\~\\ =\quad 49900+ 2\cdot\frac{100(100+1)}{2} \\~\\ =\quad 49900+ 10100\\~\\ =\quad60000\).

.
 Nov 27, 2020
 #4
avatar+312 
0

Thanks Everyone!!! :)

 Nov 28, 2020

20 Online Users

avatar
avatar
avatar