1.x^2-3x-102.x(x+y)(x-y)-x(x+y)^23.9(2a+3b)^2-4(3a-2b)^24.已知a^2+a+1=0,求a^3+2a^2+2a+3的值

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1.x^2-3x-102.x(x+y)(x-y)-x(x+y)^23.9(2a+3b)^2-4(3a-2b)^24.已知a^2+a+1=0,求a^3+2a^2+2a+3的值

1.x^2-3x-102.x(x+y)(x-y)-x(x+y)^23.9(2a+3b)^2-4(3a-2b)^24.已知a^2+a+1=0,求a^3+2a^2+2a+3的值
1.x^2-3x-10
2.x(x+y)(x-y)-x(x+y)^2
3.9(2a+3b)^2-4(3a-2b)^2
4.已知a^2+a+1=0,求a^3+2a^2+2a+3的值

1.x^2-3x-102.x(x+y)(x-y)-x(x+y)^23.9(2a+3b)^2-4(3a-2b)^24.已知a^2+a+1=0,求a^3+2a^2+2a+3的值
1.(x-5)(x+2)
2.x(x+y)[(x-y)-(x+y)]=-2xy(x+y)
3.[3(2a+3b)+2(3a-2b)][3(2a+3b)-2(3a-2b)]=13b(12a+5b)
4.a^3+2a^2+2a+3=(a^3+a^2+a)+(a^2+a+1)+2 =a(a^2+a+1)+(a^2+a+1)+2=2

^ 什么符号?

1. =(x-5)(x+2)
2. =-2xy(x+y)
3. =13b(5b+12a)
4. a^3+2a^2+2a+3=(a^3+a^2+a)+(a^2+a+1)+2
=a(a^2+a+1)+(a^2+a+1)+2=2

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