若(x-2)(x+a)=x^(2)+bx-6,则（）A.a=3,b=-5B.a=3,b=1C.a=-3,b=-1D.a=-3,b=-5如果M÷3xy=-(1/9)x^(n+1)+1/18,则M=（）A.-(1/27)x^(n)yB.-(1/3)x^(n+2)y+(1/6)xyC.-(1/3)x^(n-1)y+(1/6)xyD.(1/3)x^(n+2)y+(1/6)xy[-(1/2)x-(1/5)y]^2=

Question

若(x-2)(x+a)=x^(2)+bx-6,则 （ ）
A.a=3,b=-5 B.a=3,b=1
C.a=-3,b=-1 D.a=-3,b=-5
如果M÷3xy=-(1/9)x^(n+1)+1/18,则M= （ ）
A.-(1/27)x^(n)y B.-(1/3)x^(n+2)y+(1/6)xy
C.-(1/3)x^(n-1)y+(1/6)xy D.(1/3)x^(n+2)y+(1/6)xy
[-(1/2)x-(1/5)y]^2=_________________

Answer 1

(1)B 因为相乘为x²+（a-2）x-2a=x²+bx-6 所以a=3,b=1（2）B m=[-（1/9）x的（n+1）次方+18/1]×3xy =-（3/1）x的（n+2）次方·y+（6/1）xy(3)(1/...