已知4x2-mxy+9y2是一个完全平方式,求m的值.
计算:
(1)(2m+1)2-(2m+1)(2m-1);
(2)(2x+y-3z)2-(2x-y+3z)2.
已知x+y=-5,xy=6,则x2+y2=________.
若ax2+2x+=(2x+)2+m,则a,m的值分别是( )
A. 2,0 B. 4,0 C. 2, D. 4,
若a2-b2=8,a+b=-2,则a-b的值为( )
A. -4 B. 4 C. - D.
(1)计算:8(x4)6-2(x5·x3)3+(-3x6)3·x4·x2+x3÷x;
(2)若ax=3,b2x=2,求(a2)x-(b3x)2的值.