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:
Step-by-step explanation:
We have the equation 
In order to solve for x, we need to get all of the x's to one side and everything else to the opposite side
First, we can add 1 to each side
Now, we can add x to each side
Next, we can divide each side by 2
And here is our answer.
Answer:
That would be A) -3/5.
Step-by-step explanation:
Here it is.
Answer:
19.75. The apples cost 19.75 before the tax.
Step-by-step explanation:
0.97(x)=19.16
19.75
