2x²+y²+4x+10y+9
=2(x²+2x+1)+(y²+10y+25)-18
=2(x+1)²+(y+5)²-18
最小值是-18
被除式=除式×商+余式
所以被除式=(3x+1)×(x-1)-5
=3x²-2x-6
m^5+m^3-20m
=m(m^4+m^2-20)
=m(m^2-4)(m^2+5)
=m(m+2)(m-2)(m^2+5)
x^4n-4x^2n-45
=(x^2n-9)(x^2n+4)
=(x^n+3)(x^n-3)(x^2n+4)
(m^2-2m)^2-2m^2+4m-3
=(m^2-2m)^2-2(m^2-2m)-3
=(m^2-2m-3)(m^2-2m+1)
=(m-3)(m+1)(m-1)^2
a^4-13a^2b^2+36b^4
=(a^2-4b^2)(a^2-9b^2)
=(a+2b)(a-2b)(a+3b)(a-3b)
(x^2+4x)^2-x^2-4x-20
=(x^2+4x)^2-(x^2+4x)-20
=(x^2+4x-5)(x^2+4x+4)
=(x-1)(x+5)(x+2)^2
a^4b^4-6a^2b^2-27
=(a^2b^2-9)(a^2b^2+3)
=(ab+3)(ab-3)(a^2b^2+3)