4x+5y=98 x=y-2 解得4x+5y=98x=y-2解得

4x+5y=98 x=y-2 解得4x+5y=98x=y-2解得 x*x+2x+y*y-4y+5=0 x= y= 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 由X/Y=2Y/X-Y 怎么解得x=2y? 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 化简(2x/(x+y)-4x/(y-x))/8x(x^2-y^2)得 十万分,[3x+2y]/2=[2x+y]/3=[x-y+1]/4 解得. 若(x*x+y*y)(x*x+y*y)-4x*x*y*y=0,求代数式(x*x+5xy+y*y)/(x*x+2xy+y*y)的值 4(x-y-1)=3(1-y)-2；x/2+y/3=2 方程组的解,把①4(x-y-1)=3(1-y)-2；x/2+y/3=2化简得4X-Y=5,3X+2Y=12.把4X-Y=5乘以2得：8X-2Y=10.然后用8X-2Y=2加3X-2Y=12得 11X=22,即X=2把X=2代入4X-Y=5得 Y=3好难好难不懂啊!刚刚找到类似的 已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 5x-4y(y-x)=? (x-4y)(2x+y)= 解方程组 x+y/5+x-y/2=7 4(x+y)-5(x-y)=2 解方程组 X+Y/2+X-Y/3=6 4[X+Y]-5[X-Y]=2 解二元一次方程：x+y/2+x-y/3=6 4(x+y)-5(x-y)=2