﹙-3y的n+1次方 + 4y的n+2次方 - 12y的n次方﹚÷﹙-24y的n-1方﹚
解:y^n*y^n+3y^(n+1)*y(n-1)
=y^2n+3y^[(n+1)+(n-1)]
=y^2n+3y^2n
=4y^2n