1÷（1/x+1/y）=40*6/x+4/y=2/15这个方程咋解

已知x²+y²+6x-8x+25=0,求（x/x²-y² - 1/x+y）÷y/y-x 1.(x^3-x^2-4x+1)/(x^2-3x+2)-(x^3-2x^2-9x+21)/（x^2-5x+6）+（x^2-3x+8）/（x^2-4x+3）2.{(x^2)/（x-y)}*{y/(x+y)}-{(x^4y)/(x^4-y^4)}÷{（x^2/x^2+y^2）^2} 计算：1.y/4x²-1/12y²+1/6xy 2.3/x-6/1-x-x+5/x²-x3.x/x-y×y²/x+y-x四次方y/x四次方-y四次方÷x²/x²+y²解方程：1.x-1/（x-2）+1=1/2-x2.x+1/x-1-4/x²-1=13.1/x+3-2/3-x=1/x²-9 [(x+2y)²-（x+y)(3x-y)-5y²]÷(2x),其中x,y满足x²+4x+y²-y+17/4=0已知、x+y=6且xy=4(1)x²+y² (2)（x-y）² (3)x{四次方}+y{四次方}第一题没错 书上就这样写的！ {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 初二上学期方程题 4x+y=5 5x+4y=63x-2y=1 2x+3y=13x-2y=7 7x+5y=32x+3y=17 2x-y=-4x+5y=6 2x+y=23x-6y=4 3x+2y=52x+y=73x-4y=53x+y=1x-2y=-1x+y=42x+3y=92x-3y=74x+5y=3x+y=20004x+6y=90003x+5y=113x-2y=42x+3y=215x-2y=5x+y=54x+3y=182x+3y=16x+4y=132x+3y=40x 解分式方程组：4/（x+y）+6/(x-y)=39/(x-y)-1/(x+y)=1 x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 已知：【（x²+y²）-（x-y)²+2y（x-y)】÷4y=,求4x/（4²-y²）-1/（2x+y)的值已知：【（x²+y²）-（x-y)²+2y（x-y)】÷4y=1，求4x/（4²-y²）-1/（2x+y)的值 1.计算①(x-1-x+1分之8)×x+3分之x+1；②x+3y分之x-y÷x²+6xy+9y²分之x²-y²-x+y分之2y；③（x-x+1分之2x）÷x²-1分之x²-2x+1④（x²-2x分之x+2-x²-4x+4分之x-1）÷x³-2x²分之x-4 ｛x/60+y/80=10,x/60+y/40=15、｛2x/3+3y/4=1/5,5x/6-5y/2=2、｛5/2(x+y）=1200,10/3（x+y）=1200｛4x+5y=98,5y-4x=2、｛x/3+y/4=54/60,y/4+x/5=42/60怎么解?{40-y=x-4 40-y=y-x 若(-x+6):(x-y):(4x+y)=3:14:1,求x+y 若(-x+6):(x-y):(4x+y)=3:14:1,求x+y (-x+6):(x-y);(4x+y)=3;14:1,求x+y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 帮我做2道数学方程（1）6x-7y-40=0 5y-2x+8=0（2）（x+y)/2+(x-y)/3=6 2(x+y)-(x-y)=-4 帮我做2道数学方程（1）6x-7y-40=0 5y-2x+8=0（2）（x+y)/2+(x-y)/3=6 2(x+y)-(x-y)=-4