+36915 Arithmetic sequence with d = 18
26 + 44 + 62 + 80 + 98 + 116 + 134 = ad 'em up to see what you get !
Or use SUM = n ( a1+a7)/2 = 7 (26+134)/2 = ??
4.) d = 5 so 5n is good..... first one starts with 54 ...no good second choice only has 13 terms...no good
third choice starts with 49 and has 5n and has 14 terms.....goood! Fourth choice has 44 terms....no good
5.
n =1 = 5
2 =6
3 7
4 8 Add 5 6 7 8 and you get ?
+36915 Arithmetic sequence with d = 18
26 + 44 + 62 + 80 + 98 + 116 + 134 = ad 'em up to see what you get !
Or use SUM = n ( a1+a7)/2 = 7 (26+134)/2 = ??
4.) d = 5 so 5n is good..... first one starts with 54 ...no good second choice only has 13 terms...no good
third choice starts with 49 and has 5n and has 14 terms.....goood! Fourth choice has 44 terms....no good
5.
n =1 = 5
2 =6
3 7
4 8 Add 5 6 7 8 and you get ?
+128408 3.
Note NSS that the distances are 26, 44, 62, 80..... each successive term is 18 more than the succeeding one
The 7th term is
26 + 18 ( 7 - 1) = 26 + 18 * 6 = 134
For an arithmetic sequence.....the sum is given by :
( First term + Last term ) * number of terms / 2 =
(26 + 134) * 7 /2 = 160 * 7 / 2 = 160 / 2 * 7 = 80 * 7 = 560 ft
EP's answer to the second one is good
And for his third answer 5 + 6 + 7 + 8 =
[ 5 + 8] * 4 / 2 = 13 * 2 = 26
