3.從2開(kāi)始,將連續(xù)的偶數(shù)相加,和的情況有如下規(guī)律:
2=1×2,
2+4=6=2×3,
2+4+6=12=3×4,
2+4+6+8=20=4×5,
2+4+6+8+10=30=5×6,
2+4+6+8+10+12=42=6×7.按此規(guī)律:
(1)從2開(kāi)始連續(xù)19個(gè)偶數(shù)相加,和是
;
(2)從2開(kāi)始連續(xù)n個(gè)偶數(shù)相加,和是
;
(3)請(qǐng)用上述規(guī)律求100+102+104+…+202的值.