sequences and series

Question 1

equation for sequences

Answer 1

Un=a+(n-1)d

u= term value
n= term we are looking for
d= difference between each term
a= term 1 value

Question 2

equation for series

given 2 variables

Answer 2

Sn=n/2(2a+(n-1)d)

S= sum of series
n= term we are looking for
d= difference between each term
a= term 1 value

Question 3

what is an arithmetic sequence

Answer 3

a sequence where the difference between each term is the same

Question 4

equation for series

given 1 variable

Answer 4

Sn=n/2(a+l)

l= last term

Question 5

hard q: a circle is cut into 12 sectors whos areas are in an arithmetic sequence, the angle of the largest sector is twice the angle of the smallest sector

find size of smallest sector

Answer 5

Sn= n/2(a+l)
360=12/2(θ+2θ)
360=6(3θ)
60=3θ
θ=20