7x-12y=67 12x-7y=47 x=?y=?巧解.RT.

7x-12y=67 12x-7y=47 x=?y=?巧解.RT. 21/(x+y)+4/(x-y)=12/(x+y)+7/(x-y)结果为(x+y)/(x-y)=3求过程! 3x-7y=-24 x+y=12 |x|=7,|y|=12,且|x+y|=—(x+y),求x+y的值 已知|x|=7,|y|=12,且|x+y|=－（x+y）,求x+y的值、 2(x-2y)²-7(x-2y)³+3(2y-x)²+(2y-x)³合并同类项 这个式子2（x-2y)²-7（x-2y)³+3(2y-x)²-(2y-x)³=2（x-2y)²-7（x-2y)³+3(x-2y)²+(x-2y)³=5(x-2y)²-6(x-2y)³=(x-2y)²(5-6x+12y) 解方程组 x+y+z=-7 x-y=12 x+y-z=6 x-2y=9 x+y+z=7 2x-3y=12 已知|X|=7,|Y|=12且X>Y,求X+Y的值 已知|x|=7,|y|=12,且x>y,求x+y的值. 7x:4y,x:y=( ):( (x*x+y*y)(x*x+y*y)-(x*x+y*y)=12 求x*x+y*y等于多少 7x-12y=31 12x-7y=26x+y=?x=?可得 解之得x-y=?y=? (3x+2y)(4x-5y)-12(x+y)(x-y)+7xy,其中x=2011,y=-1, 3x-y+x=3 4【X-y-1】=3【1-y】-1 5x-4y+4x=3 2x+y-3x=11 【 x除以2 】-【y 除以3】 =2 2x+7y-3x=19 x+y+x=12 3x+2y-x=18 shuxue数学.1.5x+12y=360 7x+16y=500求x 2.x+y=36y-x=28求x x.y都是自然数,且x(x-u)-y(y-x)+12,求x.y得值快1且x(x-y)-y(y-x)=12 3Y+12=3X/8 7Y=X-3Y-12