Question

Sum in sigma notation and find the sum of each series
150+140+130+120+110+100

Answer 1

we are given

`150+140+130+120+110+100`

first term is 150

so,

`a_1=150`

now, we can find common difference

`d=140-150`

`d=-10`

now, we can find nth term

`a_n=a_1+(n-1)d`

`a_n=150+(n-1)*-10`

`a_n=-10n+160`

we can see that

total number of terms is 6

so, we can write it in sigma form as

`\sum _(n=1)^6\:\left(-10n+160\right)`

now, we can find sum

`sum=750`.............Answer