The sum of the first n odd numbers is n squared! So, the short answer is that the sum of the first 70 odd numbers is 70 squared, i.e. 4900.
Allow me to prove the result: odd numbers come in the form 2n-1, because 2n is always even, and the number immediately before an even number is always odd.
So, if we sum the first N odd numbers, we have
The first sum is the sum of all integers from 1 to N, which is N(N+1)/2. We want twice this sum, so we have
The second sum is simply the sum of N ones:
So, the final result is
which ends the proof.
Every 3 minutes they make one ton.
there are 1440 a da24H) s0 1440/3= 480
So they make about 480 tons per 24 hours
Answer:
-754.13
Step-by-step explanation:
Calculator
Answer:
I think w=6
Step-by-step explanation:
Source: trust me
The length = 6W + 7. 2L + 2W = 70. This is a system of equations. To get L by itself in the second problem, -2W from both sides to get 2L = 70 - 2W. Divide by 2 to get L = 35 - W. Now put them together. 6W +7 = 35 - W. Add W to both sides to get 7W + 7 = 35. Subtract 7 from both sides to get 7W = 28. Divide 7 to both sides to get W = 4. Now replace W with 4. 6(4) + 7 = L. 24 + 7 = 31. The length is 31. To check, do the second equation. 2(31) + 2(4) = 62 + 8 = 70. Your answer is 31.
