the answer is 250 cubic inches
It'd be easier to do #18 if y ou were to break it up:
14* (first term + 14th term)
Sum from n=1 to 14 of n = S = ---------------------------------
14 2
14(1+14)
= ---------------- = 7(15) = 105
2
The sum of twice that is 210. The sum of "1 from n=1 to n=14" is just 14.
The final sum is 210 + 14 = 224 (answer)
STR is a triangle as shown in the picture. If Luke decided to subtract 128º from 180º, that's because he understood that the sum of the internal angles in a triangle is 180º, and therefore the angles RST and TRS together make 128º.
As a result, RST will be
128º - TRS
where TRS is the angle at R, as shown in the picture
Answer:
7.72 * 10^15
Step-by-step explanation:
8*10^15 - 2.8*10^14 = 7.72 * 10^15