数学初二问题

来源：百度知道 编辑：UC知道 时间：2024/05/02 09:50:15
1, 4+(-8的立方根)+(根号16)

2,5x^2-(-2x+3)(2x+3)

分解因式:1,(2x-y)^2+8xy 2,x^2-9y^2-x+3y
最好补充过程

1.4+(-8的立方根)+(根号16)
=4+(-2)+4
=6

2.5x^2-(-2x+3)(2x+3)
=5x^2-[3^2-(2x)^2]
=5x^2-9+4x^2
=9x^2-9
=9(x^2-1)
=9(x+1)(x-1)

3.,(2x-y)^2+8xy
=4x^2-4xy+y^2+8xy
=4x^2+4xy+y^2
=(2x+y)^2

4.x^2-9y^2-x+3y
=(x^2-9y^2)-(x-3y)
=(x+3y)(x-3y)-(x-3y)
=(x-3y)(x+3y-1)

1, 4+(-8的立方根)+(根号16)
=4-2+4
=6

4+(-8的立方根)+(根号16) =4-2+4=6

5x^2-(-2x+3)(2x+3) =5x^2-(9-4x^2) =9x^2-9

(2x-y)^2+8xy =(2x+y)^2

x^2-9y^2-x+3y
=x^2-x+1/4-(9y^2-3y+1/4)
=(x-1/2)^2-(3y-1/2)^2
=(x+3y-1)(x-3y)

4+(-8的立方根)+(根号16)
=4-2+4
=6
或4+(-8的立方根)+(根号16)
=4-2-4
=-2
5x^2-(-2x+3)(2x+3)
=5x^2-9+4x^2
=9x^2-9
=9（x+1)(x-1)
(2x-y)^2+8xy
=4x^2+y^2-4xy+8xy
=4x^2+y^2+4xy
=(2x+y)^2
x^2-9y^2-x+3y
=(x^2-9y^2)-(x-3y)
=(x+3y)(x-3y)-(x-3y)
=(x-3y)(x+3y-1)

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