Each number in the sum is even, so we can remove a factor of 2.
2 + 4 + 6 + 8 + ... + 78 + 80 = 2 (1 + 2 + 3 + 4 + ... + 39 + 40)
Use whatever technique you used in (a) and (b) to compute the sum
1 + 2 + 3 + 4 + ... + 39 + 40
With Gauss's method, for instance, we have
S = 1 + 2 + 3 + ... + 38 + 39 + 40
S = 40 + 39 + 38 + ... + 3 + 2 + 1
2S = (1 + 40) + (2 + 39) + ... + (39 + 2) + (40 + 1) = 40×41
S = 20×21 = 420
Then the sum you want is 2×420 = 840.
Answer:
well the pic is blocked for me
Step-by-step explanation:
Answer:
Step-by-step explanation:11+12/square root of 16
11+(12/4)
11+3
answer is 14
Answer:
no no no! don't touch me there that is my no no square
Step-by-step explanation:
Photic zone: seaweeds and corals live here
aphotic zone: mid-ocean level where no light reaches
deep ocean floor: animals that glow are found here
Hope this helped!
