Question

how many terms of the series 10+8+6.... should be added to get the sum is -126

Answer 1

Answer:

Let the number of terms be 'n'

A/q. n/2(2×10+(n-1)(-2)=(-126)

n(10-n+1)=(-126)

11n-n^2=(-126)

n^2-11n-126=0

n^2-18n+7n-126=0

n(n-18)+7(n-18)=0

( n+7)(n-18)=0

n=(-7) or n=18

Required number of terms=18

If you like answer, please mark it as brainliest.

I hope you will love this answer.

If you have any doubts,ask me.

Follow and thank me.

Your friend-

Sahil kumar