作业帮问一道数学题..化简求值
来源：学生作业帮 编辑：作业帮 分类：数学作业 时间：2024/05/15 07:28:41
问一道数学题..化简求值
化简求值...其中x=9分之1 y=-3
化简求值...其中x=9分之1 y=-3
(x+y^2)+[2x+y^2/(1*2)]+[3x+y^2/(2*3)]+
+[3x+y^2/(3*4)]+...+[9x+y^2/(8*9)]
=x+2x+3x+...+9x+y^2[1+1/(1*2)+1/(2*3)+...+1/(8*9)]
=(1+9)*9x/2+y^2(1+1-1/2+1/2-1/3+.+1/8-1/9)
=45x+(1+1-1/9)y^2
=45x+17y^2/9
=45*1/9+17/9*(-3)^2
=5+17/9*9
=5+17
=22
+[3x+y^2/(3*4)]+...+[9x+y^2/(8*9)]
=x+2x+3x+...+9x+y^2[1+1/(1*2)+1/(2*3)+...+1/(8*9)]
=(1+9)*9x/2+y^2(1+1-1/2+1/2-1/3+.+1/8-1/9)
=45x+(1+1-1/9)y^2
=45x+17y^2/9
=45*1/9+17/9*(-3)^2
=5+17/9*9
=5+17
=22