1/2-(2x-2/3y2)+(-3/2x+1/3y^2)其中x=-1/4,y=-1/21/2x-(2x-2/3y2)+(-3/2x+1/3y^2)其中x=-1/4,y=-1/2

1/2x+(-3/2x+1/3y2)-(2x-2/3y2)= 先化简,再求值:2x2-y2+2y2-3x2-2y2+x,其中x=-1,y=2 先化简再求值.1/2-(-3/2x+1/3y2)+(2x-2/3y2), x2+2y2=1 求2x+3y2的最值 2/1(x2-y)+3/1(x-y2)+6/1(x2+y2) 若：根号【(x+3)2+y2】+根号【(x-3)2+y2】=10,则x2/16+y2/25=____ 若y1=x－1,y2=2x+1,且y1－3y2=0,则x=_____,y1+y2=_____ 怎么算. 计算(x+y/x-y + 4xy/y2-x2)(x2-9y2)/（x2+2xy-3y2） 设y1=3x-1,y2=2x+4,且y1=-2y2,求x的值 设y1=2x+1,y2=3-x,当x为何值时,y1、y2互为相反数? 已知函数y1=x-1和y2=-2x 3 当x在什么范围内时,y1>y2 -3(2x-2/3y2)+2(-3/2x+y2) 怎么化简? 解方程组 ｛3x2-y2=8 {4x2+12xy+9y2=1 {x2+2xy+y2-4=0 x2+xy+y2=4 4x2-9y2=0 x2-2xy+y2-1=0还有{x2+y2=4xy-y2+4=0x2-----x的平方 y2------y的平方 还有{2x-3y=12x2-3xy+y2-4x+3y-3=0 3y2 (2y xy2-2xy-3x-y2-2y-1因式分解. 若y1=2x+a,y2=5x-a中,y1>3,y2 2x2+xy-3y2+x+4y-1因式分解 已知函数y1=x2,y2=2x+3（1）x在什么范围内y1＞y2?（2）y1＜y2?