问题标题:
【观察:-x,3x^2,-5x^3,7x^4,...,-37x^19,39x^20,第n个式子是?】
问题描述:
观察:-x,3x^2,-5x^3,7x^4,...,-37x^19,39x^20,第n个式子是?
冈部回答:
(-1)*n(2n-1)x*n
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观察:-x,3x^2,-5x^3,7x^4,...,-37x^19,39x^20,第n个式子是?