4(x+y)=36,72-6x=2(72-6y)解方程

x+y=24 2x+4y=72 4(x+y)=36,72-6x=2(72-6y)解方程 3(x+y)+2(x-y)=36 4(x+y)-5(x-y)=2 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 （x+y）/2- x-y/2=6 3(x+y)=4(x-y) x+y/3+x-y/2=6 4(x+y)-2(x-y)=40 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 2X-3Y=12 3X-4Y=17加减消元法3x+2y=94x-2y=52x-3y=123x-4y=175x-5y=715x+20y=72x+3y=56x-5y=-6 因式分解x²+x-72 -x²-6x+10 若x、y满足2x+y-4=0求xy的最大值 化简求值:(x+y)+(2x+1/2y)+(3x+1/6y)+.+(9x+1/72y) ,其中x=1,y=-9 (x+y)+(2x+0.5y)+(3x+1/6y)+...+(9x+1/72y),当x=2,y=9时,求代数式的值 1.(x-2y)(x+2y)-(x平方+y)(x平方-y) 2.(2x-y)(y+2x)-(2y+x)(2y-x)3.已知：x+y=6,x平方-y平方=48,求x,y的值4.x平方-2x分之x+2 -- x平方-4x+4分之x-1 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 求值域 1,y=(x+2)/(x*x+3x+6) 2,y=3x/(x*x+4) 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7