八上几道因式分解的题,求解答!用提公因式法和公式法解分组分解①3x^4y^2-12x^3yz②-4xy^3+8xy^2-
3个回答
①3x^4y^2-12x^3yz
=3x³y(xy-4z)
②-4xy^3+8xy^2-16xy
=-4xy(y²-2y+4)
③4（m-n）^3+8(n-m)^2
=4(m-n)³+8(m-n)²
=4(m-n)²(m-n+2)
④a(2a-b)-2b(b-2a)
=a(2a-b)+2b(2a-b)
=(2a-b)(a+2b)
⑤x^2-9y^2
(x-3y)(x+3y)
⑥3ab^3-3ab
=3ab(b²-1)
=3ab(b-1)(b+1)
⑦(5m-2n)^2-9(m+n)^2
=(5m-2n-3m-3n)(5m-2n+3m+3n)
=(2m-5n)(8m+n)
⑧1.73^2-0.73^2
=(1.73-0.73)(1.73+0.73)
=1*2.46
=2.46
⑨9a^2+6a+1
=(3a+1)²
第十题
x^3y-6x^2y^2+9xy^3
=xy(x²-6xy+9y²)
=xy(x-3y)²
第十一题
(a^2+4b^2)^2-16a^2b^2
=(a²+4b²-4ab)(a²+4b²+4ab)
=(a-2b)²(a+2b)²
第十二题
x^2+4x-y^2-6y-5
=x²+4x+4-y²-6y-9
=(x+2)²-(y+3)²
=(x+2+y+3)(x+2-y-3)
=(x+y+5)(x-y-1)
第十题的题目是错的
