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已知N^2+N-1=0,则N^3+2N^2+2006=?已知X+5Y=6,则X^2+5XY+30Y=?

题目详情
已知N^2+N-1=0,则N^3+2N^2+2006=?
已知X+5Y=6,则X^2+5XY+30Y=?
▼优质解答
答案和解析
n^3+2n^2+2006
=n^3+n^2+n^2+2006
=n(n^2+n)+n^2+2006
=n+n^2+2006
=2007
x^2+5xy+30y
=x(x+5y)+30y
=6x+30y
=6(x+5y)
=36