Question

Due tomorrow. Please help!!!!

Answer 1

The common difference can be found from

`d=(a_(17)-a_(7))/(17-7)=(81-41)/(17-7)=(40)/(10)=4`
The first term of the sequence can be found from either of the given terms.

`a_(7)=41=a_(1)+(7-1)d=a_(1)+24\\a_(1)=41-24=17`

The sum of 40 terms is

`S_(40)=(40)/(2)(a_(1)+a_(40))=20(17+(17+39\cdot 4)=20\cdot 190=3800`

The sum of the first 40 terms is 3800.