I think this might be the Answer
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)
You multiply 0.4 by 4.2 and that equals 1.68 so sumeet uses 1.68 gallons of gas in 4.2 hours.
Answer:-1
Step-by-step explanation:3-4=-1
A true
because 53•(41•11)=23,903 and (53•41)•11=23,903
Hope this helped
