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?
答
(-1)*n(2n-1)x*n
观察:-x,3x^2,-5x^3,7x^4,...,-37x^19,39x^20,第n个式子是?
(-1)*n(2n-1)x*n