a2=a1+d
a5=a1+4d
2a1+5d=4 ==> d=2/3
an=a1+(n-1)d=33 1+2(n-1)=99 n=50
等差数列(an)中,已知a1等于三分之一,a2加a5等于4,an等于33,则n为?
等差数列(an)中,已知a1等于三分之一,a2加a5等于4,an等于33,则n为?
数学人气:177 ℃时间:2019-12-14 09:42:35
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