4x+5y=3.5 x-1=1.8-x-6y解这个方程组

解方程组4x+5y=3.5,x-1=1.8-x-6y 4x+5y=3.5 x-1=1.8-x-6y解这个方程组 y=|-x.x+4x+5| 若2x-3y+4=0则x（x*x-1)+x(5-x*x)-6y+7 5x-4y(y-x)=? 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 x-y+5x-4x= ?x-y+5x-4x= ? 求y=(5x-1)/(4x+2) (x 5(x-y)³-3（x-y）²+7(x-y)-5(x-y)³+（x-y）²-5（x-y）,其中,x-y=1/3.5(x-y)³-3（x-y）²+7(x-y)-5(x-y)³+（x-y）²-5（x-y）,其中,x-y=1/3先化简,再求值； xy²/(x²y-y) × x²/(x²+x)=(x²-3x)/(x²-5x) × 2x-10/(x²-6x+9)=化简求植x²-1/(x²-x-2)除以x/2x-4,其中x=1/2[x-x/(x+1)]除以[x/(2x-4)] ,其中x=√2+1 高数求极限 y=[(3^x +4^x +5^x)/3]^(1/x) (x->0) {x+y=1 ,xy=-6{x(2x-3)=0,y=x²-1{(3x+4y-3)(3x+4y+3)=0,3x+2y=5{(x-y+2)(x+y)=0,x²+y²=8{(x+y)((x+y-1)=0,(x-y)(x-y-1)=0 （x+2y)(x-2y)(x^2-4y^2),其中x=2,y=-1（x+5)^2-(x-5)^2-5(2x+1)(2x-1)+x·(2x)^2,其中x=-1 化简求值{(x=2y)(5x-2y)-(3x+2y)(3x-2y)]/4x,其中x=2,y=-1 x*x+2x+y*y-4y+5=0 x= y= （5x+3y)(3y-5x)-(4x-y)(4y+x)= {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 4(x-y)-3(x-y)=9 5(x-y)+2(x-y)=11