以下五道因式分解哪些是错的?怎样改正?1.4(x-y)^2-9(x+y)^2=2^2(x-y)^2-3^2(x+y)^2=(2+3)(2-3)[(x-y)+(x+y)]*[(x-y)-(x+y)]=5*(-1)*2x*(-2y)=20xy2.a^2-4-a+2=(a+2)(a-2)-(a+2)=(a+2)(a-2-1)=(a+2)(a-3)3.a^8-b^8=(a^4)^2-(b^4)^2=(a^4+b^4)(a^4-b^4)4
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![以下五道因式分解哪些是错的?怎样改正?1.4(x-y)^2-9(x+y)^2=2^2(x-y)^2-3^2(x+y)^2=(2+3)(2-3)[(x-y)+(x+y)]*[(x-y)-(x+y)]=5*(-1)*2x*(-2y)=20xy2.a^2-4-a+2=(a+2)(a-2)-(a+2)=(a+2)(a-2-1)=(a+2)(a-3)3.a^8-b^8=(a^4)^2-(b^4)^2=(a^4+b^4)(a^4-b^4)4](/uploads/image/z/11483173-37-3.jpg?t=%E4%BB%A5%E4%B8%8B%E4%BA%94%E9%81%93%E5%9B%A0%E5%BC%8F%E5%88%86%E8%A7%A3%E5%93%AA%E4%BA%9B%E6%98%AF%E9%94%99%E7%9A%84%3F%E6%80%8E%E6%A0%B7%E6%94%B9%E6%AD%A3%3F1.4%28x-y%29%5E2-9%28x%2By%29%5E2%3D2%5E2%28x-y%29%5E2-3%5E2%28x%2By%29%5E2%3D%282%2B3%29%282-3%29%5B%28x-y%29%2B%28x%2By%29%5D%2A%5B%28x-y%29-%28x%2By%29%5D%3D5%2A%28-1%29%2A2x%2A%28-2y%29%3D20xy2.a%5E2-4-a%2B2%3D%28a%2B2%29%28a-2%29-%28a%2B2%29%3D%28a%2B2%29%28a-2-1%29%3D%28a%2B2%29%28a-3%293.a%5E8-b%5E8%3D%28a%5E4%29%5E2-%28b%5E4%29%5E2%3D%28a%5E4%2Bb%5E4%29%28a%5E4-b%5E4%294)
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以下五道因式分解哪些是错的?怎样改正?1.4(x-y)^2-9(x+y)^2=2^2(x-y)^2-3^2(x+y)^2=(2+3)(2-3)[(x-y)+(x+y)]*[(x-y)-(x+y)]=5*(-1)*2x*(-2y)=20xy2.a^2-4-a+2=(a+2)(a-2)-(a+2)=(a+2)(a-2-1)=(a+2)(a-3)3.a^8-b^8=(a^4)^2-(b^4)^2=(a^4+b^4)(a^4-b^4)4
以下五道因式分解哪些是错的?怎样改正?
1.4(x-y)^2-9(x+y)^2
=2^2(x-y)^2-3^2(x+y)^2
=(2+3)(2-3)[(x-y)+(x+y)]*[(x-y)-(x+y)]
=5*(-1)*2x*(-2y)
=20xy
2.a^2-4-a+2
=(a+2)(a-2)-(a+2)
=(a+2)(a-2-1)
=(a+2)(a-3)
3.a^8-b^8
=(a^4)^2-(b^4)^2
=(a^4+b^4)(a^4-b^4)
4.x^3+3x^2-2x-6
=x^2(x+3)-2(2x+3)
=(x+3)(x^2-2)
=(x+3)(x-2)(x+2)
5.15x^3n+9x^2n-6x^n
=3x^n(5x^2+3x-2)
=3x^n(5x+2)(x-1)
以下五道因式分解哪些是错的?怎样改正?1.4(x-y)^2-9(x+y)^2=2^2(x-y)^2-3^2(x+y)^2=(2+3)(2-3)[(x-y)+(x+y)]*[(x-y)-(x+y)]=5*(-1)*2x*(-2y)=20xy2.a^2-4-a+2=(a+2)(a-2)-(a+2)=(a+2)(a-2-1)=(a+2)(a-3)3.a^8-b^8=(a^4)^2-(b^4)^2=(a^4+b^4)(a^4-b^4)4
1,=(2x-2y)*(2x-2y)-(3x+3y)*(3x+3y)
=(2x-2y-3x-3y)*(2x-2y+3x+3y)
=-(5x+y)(x+5y)
2.a^2-4-a+2
=(a+2)(a-2)-(a-2)
=(a-2)(a+2-1)
=(a-2)(a+1)
3.a^8-b^8
=(a^4)^2-(b^4)^2
=(a^4+b^4)(a^4-b^4)
=(a^4+b^4)(a^2-b^2)(a^2+b^2)
=(a^4+b^4)(a-b)(a+b)(a^2+b^2)
4.x^3+3x^2-2x-6
=x^2(x+3)-2(x+3)
=(x+3)(x^2-2)
5.15x^3n+9x^2n-6x^n
=3x^n(5x^2n+3x^n-2)
=3x^n(5x^n-2)(x^n+1)