作业帮(x^2-x-2)(x^2+11x+28)-19
来源：学生作业帮 编辑：作业帮 分类：数学作业 时间：2024/05/25 03:36:22
(x^2-x-2)(x^2+11x+28)-19
用换元法
用换元法
(x^2-15x+54)(x^2+11x+28)+350
=(x-6)(x-9)(x+4)(x+7)+350
=[(x-6)(x+4)][(x-9)(x+7)]+350
=(x^2-2x-24)(x^2-2x-63)+350
设u=x^2-2x,则
(x^2-2x-24)(x^2-2x-63)+350
=(u-24)(u-63)+350
=u^2-87u+1862
=(u-38)(u-49)
=(x^2-2x-38)(x^2-2x-49)
=(x-1+√39)(x-1-√39)(x-1+5√2)(x-1-5√2)
=(x-6)(x-9)(x+4)(x+7)+350
=[(x-6)(x+4)][(x-9)(x+7)]+350
=(x^2-2x-24)(x^2-2x-63)+350
设u=x^2-2x,则
(x^2-2x-24)(x^2-2x-63)+350
=(u-24)(u-63)+350
=u^2-87u+1862
=(u-38)(u-49)
=(x^2-2x-38)(x^2-2x-49)
=(x-1+√39)(x-1-√39)(x-1+5√2)(x-1-5√2)
x-1)(X-2)(x-3)...(x-50)+x(x-2)(X-3)...(X-50)+...+x(x-1)(x-2)
解方程 x*x*x + 2*x -19 =0
(2x-1)/(x-1)(x-2)=(x-5)/(x-2)(x-3) x/2x^2-11x-21=(x+7)/x^2-1
求x^2-3x/x^2-6x+9*x^2-11x+30/x^2-5x-1
x^2+x-2
[1/(x-1)(x+2)]+[1/(x+2)(x+5)]+[1/(x+5)(x+8)]+[1/(x+8)(x+11)]
x(x+2)
x^2+x+a
2x²+x
{2X+1}+{X}
|2x-log2^x|
x^2-3x