已知数列{an}满足:a1=1,且an-an-1=2n,求(1)a2,a3,a4.(2)求数列{an}的通项an

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已知数列{an}满足:a1=1,且an-an-1=2n,求(1)a2,a3,a4.(2)求数列{an}的通项an已知数列{an}满足:a1=1,且an-an-1=2n,求(1)a2,a3,a4.(2)

已知数列{an}满足:a1=1,且an-an-1=2n,求(1)a2,a3,a4.(2)求数列{an}的通项an
已知数列{an}满足:a1=1,且an-an-1=2n,求(1)a2,a3,a4.(2)求数列{an}的通项an

已知数列{an}满足:a1=1,且an-an-1=2n,求(1)a2,a3,a4.(2)求数列{an}的通项an
an-an-1=2n
……
a2-a1=2
an -a1=2+……+2n=n*(n-1)
an=n*(n-1)+1

累加法会用不 ?
an-an-1=2n
a(n-1)-a(n-2)=2(n-1)


a2-a1=2 等式左边相加,右边相加 结果不就出来了?