Question

in an AP is an=2-3 , find the sum of first 12 trems​

Answer 1

Answer:

Step-by-step explanation:

Heya!

An = 2 - 3n

put n = 1 to get ist term

A1 = 2 - 3×1 = -1

put n = 2 to get 2nd term

A2 = 2 - 3×2 = -4

Put n = 3 to get 3rd term

A3 = 2 - 3×3 = -7

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put n = 12 to get 12th term

A12 = 2 - 3×12 = -34

So, Series becomes

-1 , -4 , -7 , ... , -34

It's sum is given by

S12 = 6 { -1 -34 }

S12 = -210

So, sum of ist 12 term is -210