-2^10x^2-x^2y+2π-2是次项式,常数项是,最高次项是.(2x-1)(-1-2x)=(-a+2b)(a^2+2ab+4b^2)=已知(3x+y+6)^2+|x-2y-5|=0,则x/y=

Question

-2^10x^2-x^2y+2π-2是_______次_______项式,常数项是______,最高次项是______.
(2x-1)(-1-2x)=______
(-a+2b)(a^2+2ab+4b^2)=_______
已知(3x+y+6)^2+|x-2y-5|=0,则x/y=

Answer 1

1）-2^10x²-x²y+2π-2是3次3项式,常数项是2π、2,最高次项是x²y.
2）(2x-1)(-1-2x)=-(2x-1)(2x+1)=-(4x²-1)=1-4x²
3）(-a+2b)(a²+2ab+4b²)=(2b-a)［(2b)²+2ab+a²］=8b³-a³
4）已知(3x+y+6)²+|x-2y-5|=0
∵|x-2y-5|≥0
∴(3x+y+6)²≤0
3x+y+6≤0
3x+y≤-6----------------------(1)
∵|x-2y-5|≥0
∴x-2y-5≥0
x-2y≥5
-x+2y≤-5--------------------------(2)
x-2y-5≤0
x-2y≤5---------------------------(3)
由(1)和(2)组成不等式组解得：x≥-1,y≤-3
由(1)和(3)组成不等式组解得：x≤-1,y≤-3
∴x=-1,y=-3
则x/y=-1/(-3)=1/3