天空灰骛
幼苗
共回答了12个问题采纳率:83.3% 举报
10×16×22=【10×16×22×28-4×10×16×22】/24
16×22×28=【16×22×28×34-10×16×22×28】/24
…………
76×82×88=【76×82×88×94-70×76×82×88】/24所以原式=【10×16×22×28-4×10×16×22】/24+【16×22×28×34-10×16×22×28】/24+…………+【76×82×88×94-70×76×82×88】/24=【76×82×88×94-4×10×16×22】/24=【51551104-14080】/24=2147376
对于类似的等差数列连乘求和,有个通式:
a(a+h)(a+2h)+(a+h)(a+2h)(a+3h)+…………(a+kh)(a+(k+1)h)(a+(k+2)h)=[(a+kh)(a+(k+1)h)(a+(k+2)h)(a+(k+3))h-(a-h)a(a+h)(a+2h)]/4h
1年前
1