数列{an}中,相邻两项an,an+1是方程x2+3nx+bn=0的两根,已知a10=-17,则b51的值等于( ) A.5800 B.5840 C.5860 D.6000
数列{an}中,相邻两项an,an+1是方程x2+3nx+bn=0的两根,已知a10=-17,则b51的值等于( )
A. 5800
B. 5840
C. 5860
D. 6000
A. 5800
B. 5840
C. 5860
D. 6000
数学人气:325 ℃时间:2020-02-21 08:35:15
优质解答
∵an,an+1是方程x2+3nx+bn=0的两根,∴an+an+1=-3n,an•an+1=bn.∴an+2-an=(an+2+an+1)-(an+1+an)=-3(n+1)-(-3n)=-3∴a1,a3,…,a2n+1和a2,a4,…,an都是公差为-3的等差数列,∴a52=a10+21(-3)=-80...
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