7. 試求下列級數和:
(1) 1 x 1 + 2 x 3 + 3 x 5 + ... ... + 29 x 57 + 30 x 59 =
(+ + +.
(2) 11² + 122 + 132 + ... +592 + 60° = 1342
+ 。
十、、
=
o
NET
ICHI +2/2+1) + 31 3+2) + 29 (29+28) + 30130
39 (29+28)
= (1 +1+12 +2 +3 + 6) + (29* + 812) + (31
= 1
(P + 2 + 3 tout 30 ) + (1+246 + - + 870)
(1
2
