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(x^2-2x-15)(x^2-4x-60)-20x^2=(a+b-2ab)(a+b-2)+(1-ab)^2=x^3-19x-30=x^4+1993x^2+1992x+1993=x(y+z)^2+y(z+x)^2+z(x+y)^2-4xyz=a^5+a+1=a^4+b^4+c^4-2a^2b^2-2b^2c^2-2c^2a^2=(a+b+c)(bc+ca+ab)-abc=

题目详情
(x^2-2x-15)(x^2-4x-60)-20x^2=
(a+b-2ab)(a+b-2)+(1-ab)^2=
x^3-19x-30=
x^4+1993x^2+1992x+1993=
x(y+z)^2+y(z+x)^2+z(x+y)^2-4xyz=
a^5+a+1=
a^4+b^4+c^4-2a^2b^2-2b^2c^2-2c^2a^2=
(a+b+c)(bc+ca+ab)-abc=
▼优质解答
答案和解析
(x^2-2x-15)(x^2-4x-60)-20x^2=(-30 - 9 x + x^2) (-30 + 3 x + x^2)
(a+b-2ab)(a+b-2)+(1-ab)^2=(-1 + a)^2 (-1 + b)^2
x^3-19x-30=(-5+x)(2+x)(3+x)
x^4+1993x^2+1992x+1993=(1993 - x + x^2) (1 + x + x^2)
x(y+z)^2+y(z+x)^2+z(x+y)^2-4xyz=(x + y) (x + z) (y + z)
a^5+a+1=(1 + a + a^2) (1 - a^2 + a^3)
a^4+b^4+c^4-2a^2b^2-2b^2c^2-2c^2a^2=(a - b - c) (a + b - c) (a - b + c) (a + b + c)
(a+b+c)(bc+ca+ab)-abc=(a + b) (a + c) (b + c)