1.（-2a^2)^3-6a^2*a^4
3个回答
（-2a^2)^3-6a^2*a^4
=-8a^6-6a^6
=-14a^6
（3x+1)^2(3x-1)^2
=[(3x+1)(3x-1)]^2
=(9x^2-1)^2
=81x^4-18x^2+1
(3x-4y)^2-(3x+4y)^2-(4x+3)（4x-3)
=(3x-4y+3x+4y)(3x-4y-3x-4y)-(16x^2-9)
=-48xy-16x^2+9
(2a+b-3)(2a-b-3)
=[(2a-3)+b][(2a-3)-b]
=(2a-3)^2-b^2
=4a^2-12a+9-b^2
-a·a^5-(a^2）^3-(-2a^3)^2
=-a^6-a^6-4a^6
=-6a^6
3x^2·x^n-2+3（-x)^2·x^n-3·(-x)
=3x^n-3^n
=0
(-3*3^-2)^-3-(-3^2)^2/3^2*2005^0
=-3^3-3^2
=-27-9
=-36
已知a-1/a=1,求a^2+1/a^2和a^4+1/a^4
a^2+1/a^2
=(a-1/a)^2+2
=1^2+2
=3
a^4+1/a^4
=(a^2+1/a^2)^2-2
=3^2-2
=9-2
=7
如果x^2+x-1=0,求x^3+2x^2+3
因为x^2+x-1=0
所以x^2=1-x
x^2+x=1
所以x^3+2x^2+3
=x^2(x+2)+3
=(1-x)(x+2)+3
=-x^2-x+2+3
=-(x^2+x)+5
=-1+5
=4
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