在等差数列{an}中,a1+a2+a3=3,a5=10,求公差d以及a10
人气:315 ℃ 时间:2020-05-11 13:55:45
解答
an=a1+(n-1)d
a1+a2+a3=a1+a1+d+a1+2d=3
a1+d=1
a5=a1+4d=10
解得a1=-2,d=3
a10=a1+9d=25
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