a3=b3得到a1+2d=b1*q^2,2d=a1*(q^2-1)
a7=b5得到a1+6d=b1*q^4,6d=a1*(q^4-1)
两式相除,得到q^2=2,d=a1/2
几个选项代一下,选C
已知公差不为0的等差数列an与等比数列bn,a1=bi,a3=b3,a7=b5
已知公差不为0的等差数列an与等比数列bn,a1=bi,a3=b3,a7=b5
如题,A）b11=a13,B) b11=a31,C) b11=a63,D) b63=a11
如题,A）b11=a13,B) b11=a31,C) b11=a63,D) b63=a11
数学人气：288 ℃时间：2019-08-20 20:12:15
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