(x+a)(x+b)=x^2+(a+b)x+ab=x^2+mx-10
所以a+b=m,ab=-10=1*(-10)=(-1)*10=(-2)*5=2*(-5)
所以a和b分别等于1,-10或-10,1或-2,5或2,-5
m=a+b=-9或9或3或-3
(a-1)(a+1)=a^2-1
由乘法分配律
(a-1)(a+1)=a(a+1)-1*(a+1)=a^2+a-a-1=a^2-1
(a^2*b-2ab^2-b^3)÷b－(a+b)(a-b),
=a^2*b÷b-2ab^2÷b-b^3÷b－(a^2-b^2)
=a^2-2ab-b^2-a^2+b^2
=-2ab
=-2*(1/2)*(-1)
=1
[(3x+4y)^2－3x(3x+4y)]÷(-4y)
=(9x^2+24xy+16y^2-9x^2-12xy)÷(-4y)
=(12xy+16y^2)÷(-4y)
=12xy÷(-4y)+16y^2÷(-4y)
=-3x-4y
(1)5(x-2)-x(2-x)
=5(x-2)+x(x-2)
=(x-2)(x+5)