初一数学...么么哒...↖(^ω^)↗

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初一数学...么么哒...↖(^ω^)↗
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初一数学...么么哒...↖(^ω^)↗
初一数学...么么哒...↖(^ω^)↗

 

初一数学...么么哒...↖(^ω^)↗
因3x^2-x=1所3x^2=x+1
所6x^3+7x^2-5x+2006
=x(6x^2+7x-5)+2006
=x(2x-1)(3x+5)+2006
=(2x-1)(3x^2+5x)+2006
=(2x-1)(1+x+5x)+2006
=(2x-1)(6x+1)+2006
=12x^2-4x-1+2006
=4(3x^2-x)+2005
=4*1+2005
=2009

因为3x^2-x=1,所以3x^2=x+1
所以6x^3+7x^2-5x+2006
=x(6x^2+7x-5)+2006
=x(2x-1)(3x+5)+2006
=(2x-1)(3x^2+5x)+2006
=(2x-1)(1+x+5x)+2006
=(2x-1)(6x+1)+2006
=12x^2-4x-1+2006
=4(3x^2-x)+2005
=4*1+2005
=2009