2ax+3y=5,4x-y=-1,5x+y-3z=13无解.求a

5x-3y=-4ax+5y=a+2x+y=0 ax-2y=1 ax+2y=5 x=2y求a 请解答方程组：（39）2x+y=5 (40)x+y=7 (41)2x+3y=12 (42)2x+y=3ax+3y=7 2x-y=8 3x+4y=17 3x-5y=11(43)3x+y=82 (44)3(x-1)=y+5 45 x/4+y/3=7 (46)x+y/3 +x-y/2=610x-11y=87 5(y-1)=3(x+5) 2/3x+y/2=14 3(x+y-)2(x-y)=28 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 数学题：已知方程组(1)：5X+Y=3,AX+5Y=4与方程组(2)：X 已知方程组:5x+y=3 ; ax+5y=4与方程组x 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 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) ax-3y=1 x+by=5 已知函数y=x^2-ax-3(-5 先化简再求值(x-y)(x-2y)+(x-2y)(x-3y)-2(x-3y)(x-4y) x=4 y=5 y'(x)=-5x.y(x)+ax求方程不是。是乘y(x) 1 若（x+m）（x+2）=x的平方-6x+n,则m= n= 2 若（2x-3）（5-2x）=ax的平方+bx+c,则a+b+c= 3 (2x-3y)(2x-3y)-（y+3x)(3x-y)4 (3x+2y)(2x+3y)-(x-3y)(3x+4y) {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? {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.y满足方程组（3ax+4y=9 （6ax+5y=27,那么3ax+y的值是?