课外习题：因式分解（十字相乘法）2x^3+6x^2+4xx^4-6x^2+8x^4-13x^2+36(x-2y)^2-2(x-2y_数学解答

课外习题：因式分解（十字相乘法）
2x^3+6x^2+4x
x^4-6x^2+8
x^4-13x^2+36
(x-2y)^2-2(x-2y)-24
7x^2-2xy-5y^2

人气：361 ℃　时间：2020-04-13 07:16:26

解答

2x^3+6x^2+4x=x(2x+2)(x+2)
x^4-6x^2+8 =(x^2-2)(x^2-4)
x^4-13x^2+36 =(x^2-4)(x^2-9)
(x-2y)^2-2(x-2y)-24 = (x-2y+4)(x-2y-6)
7x^2-2xy-5y^2 ==(7x+5y)(x-y)