my1202 What's an Arithmetic Sequence?

3178 days ago by MATH4R2012

#1){3*n+1}={4,7,10,13} [3*n+1 for n in range(1,5)] 
       
sum([3*n+1 for n in range(1,5)]) 
       
#2){3*n+5}={5,8,11,14} [3*n+5 for n in range(4)] 
       
sum([3*n+5 for n in range(4)]) 
       
#3){4-n}={4,3,2,1,0,-1} [4-n for n in range(6)] 
       
sum([4-n for n in range(6)]) 
       
#4){2,6,10,...}=? [4*n-2 for n in range(1,6)] 
       
#4)13th term? [4*n-2 for n in range(1,14)] 
       
#4)sum of 13 terms? (2+50)/2*13 
       
#p829(52) {100,98,96,...} [-2*n+102 for n in range(1,10)] 
       
#p829(52) 30th step? [-2*n+102 for n in range(1,31)] 
       
#p829(52) how many bricks? (100+42)/2*30 
       
#p829(53) {10,14,18,...} [4*n+6 for n in range(1,10)] 
       
#p829(53) how many rows if whole section has 2040 seats? equ=(10+(4*x+6))/2*x==2040;show(equ) equ=expand(equ);show(equ) equ=equ-2040;show(equ) equ=factor(equ);show(equ) solve(equ,x) 
       




[4*n+6 for n in range(1,31)] 
       
(10+126)/2*30 
       
plot(2*x^2+8*x-2040,-50,50)