Find the best solutions to your problems with the help of IDNLearn.com. Discover reliable and timely information on any topic from our network of experienced professionals.

Find the sum of the first 40 terms of the arithmetic sequence.
14, 4, -6, -16, -26, -36


Sagot :

Answer:

-7240

Step-by-step explanation:

The nth term is -10n + 24.

So the combination of the first and second term would be (-10+24)+(-10x2+24) and this would continue for the first 40 terms so the 24s would add up to 24x40=960. Meanwhile, the -10s would keep adding up so it would be -10-20-30-40.... which you can simplify by making it -10(1+2+3+4) all the way to 40 to make the calculation easier... u can further simplify by making 41 = one pair of numbers so 40+1, 39+2 until you get 21+20 so ur left with -10(20 pairs of 41) so -10(20x41) = -10(820)= -8200.

Add this to your initial 960 so

-8200 +960 = -7240

Hope this helps