数列An,A1=-60,A(n+1)=(An)+3,n属于正整数,则该数列前30项的绝对值之和为?
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![数列An,A1=-60,A(n+1)=(An)+3,n属于正整数,则该数列前30项的绝对值之和为?](/uploads/image/z/11628372-12-2.jpg?t=%E6%95%B0%E5%88%97An%2CA1%3D-60%2CA%28n%2B1%29%3D%28An%29%2B3%2Cn%E5%B1%9E%E4%BA%8E%E6%AD%A3%E6%95%B4%E6%95%B0%2C%E5%88%99%E8%AF%A5%E6%95%B0%E5%88%97%E5%89%8D30%E9%A1%B9%E7%9A%84%E7%BB%9D%E5%AF%B9%E5%80%BC%E4%B9%8B%E5%92%8C%E4%B8%BA%3F)
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数列An,A1=-60,A(n+1)=(An)+3,n属于正整数,则该数列前30项的绝对值之和为?
数列An,A1=-60,A(n+1)=(An)+3,n属于正整数,则该数列前30项的绝对值之和为?
数列An,A1=-60,A(n+1)=(An)+3,n属于正整数,则该数列前30项的绝对值之和为?
这是等差数列,An=3n-63
3n-63>0推出n>21所以前20项是负的
绝对值之和=S30-2*S20=765