1.已知:x^2+mx+n乘以x+2得到的积为x^3+2x+12,求m,n

1.已知:x^2+mx+n乘以x+2得到的积为x^3+2x+12,求m,n
2.2^2009*5^2011的积有多少个0?是几位数?
3.有理数x,y,z满足｜x-y-2｜+（3x-6y-7）^2+｜3y+3z-4｜=0,求x^3n y^3n+1 z^4n-x的值 （n是正整数） 求x,y,

1.(x^2+mx+n)*(x+2)=x^3+2x^2+mx^2+2mx+nx+2n=x^3+(2+m)x^2+(2m+n)x+12n=x^3+2x+12
2+m=0 2m+n=2 2n=12
m=-2 n=6
2.2^2009*5^2011=10^2009*5^2 有2009个0,2500...000.共2011位数.
3.｜x-y-2｜+（3x-6y-7）^2+｜3y+3z-4｜=0
x-y-2=0 3x-6y-7=0 3y+3z-4=0
x=5/3 y=-1/3 z=5/3
剩下就可以自己求了.