20-9y-20y^2

9y^2+3y-20快9y^2+3y-20=(3y+5)(3y-4)如果本题有什么不明白可以追问,另外发并点击我的头像向我求助,请谅解,

-1+y+20y^2-1+y+20y^2=20y^2+y-1=(4y+1)(5y-1)

2x+3y=9x+y=20把x+y=20转换成x=20-y代入到前面的式子得出2（20-y）+3y=940+y=9y=-31代入x+y=20得出x=51所以x=51y=-31

y(3y^2+8y-3)-6y(3y+2y-1)+9y求导?求偏导?求微分?给题目呀

9y方+3y-203y方+11y+102x方-9x-356x方-11xy+3y方3m方-7mn-6n方5题都用十字相乘法9y方+3y-20=(3y-4)(3y+5)3y方+11y+10=(3y+5)(y+2)2x方-9x-35=(2x+5)

4y-3(20-y)=6y-7(9-y)解方程4y-3(20-y)=6y-7(9-y)4y-60+3y=6y-63+7y3=6yy=1/24y-3(20-y)=6y-7(9-y)4y-60+3y=6y-63+7y7y-60=13y-6313

4y-3(20-y)=6y-7(9-y)咋解?4y-3(20-y)=6y-7(9-y)去括号4y-60+3y=6y-63+7y移项6y=-60+63=3y=3/6=1/24y-3(20-y)=6y-7(9-y)去括号4y-60+3y=6y-

4y-3(20-y)=6y-7(9+y)解方程4y-3(20-y)=6y-7(9+y)4y-60+3y=6y-63-7y7y-6y+7y=-63+608y=-3y=-3/87y-60=-63-y8y=-3y=-3/84y-603y=6y-6

4y-3(20-y)=6y-7(9-y)这个,4y-3（20-y）=6y-7（9-y）把他们全部乘出来4y-60+3y=6y-63+7y然后合并同类项得:3=6y最后得出y=1/2解:原方程=>4y-60+3y=6y+7y-633=6yy=

解方程：4y-3(20-y)=6y-7(9-y)4y-3(20-y)=6y-7(9-y)4y-60+3y=6y-63+7y7y-60=13y-6313y-7y=63-606y=3y=1/2

4y-3(20-y)=6y-7(9-y) 4y-60+3y=6y-63+7y6y=3y=1/2外等于0.5

因式分解,5y（x-2y）²-20y（2x-y）²5y（x-2y）²-20y（2x-y）²=5y[(x-2y)²-4(2x-y)²]=5y[(x-2y)+2(2x-y)][(x-2

x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20由(1)得3x+3y+2x-2y=365x+y=36(3)由(2)得4x+4y-3x+3y=-20x+7y=-20(4)(3)×7-(4)得34x=272∴x=8把x=8代入(3

{(x+y)/2+(x-y)/3=64(x+y)-3(x-y)=-20{(x+y)/2+(x-y)/3=63(x+y)+2(x-y)=36(1)4(x+y)-3(x-y)=-20(2)由（1）*3+(2)*2得9(x+y)+6(x-y)+8

4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6第二个方程是不是写错了2/（x+y）+3/（x-y）=6是这样吗

(-20+y)(y+8)+75(-20+y)(y+8)+75=y²-20y+8y-160+75=y²-12y-85=(y+5)(y-17)(-20+y)(y+8)+75=y²-12y-85=（y-17）（y+5

方程组：x(y+1)+2(y+1)=y(y-1)x-5(y-1)x（4+y）-y（8-x）=-20x(y+1)+2(y+1)=y(y-1)x-5(y-1)x（4+y）-y（8-x）=-20（这是一个方程组.）1\先将X(Y+1)+2(Y+1

X+X+X+Y+Y=20X+Y+Y=14.6x=?Y=?速度啊1分钟时间X+X+X+Y+Y=20X+Y+Y=14.6x=?Y=?速度啊1分钟时间20错了是25啊3X+2Y=20X+2Y=14.6那么X=2.7Y=5.95

通分y+3/y*y-6y+9,1/2y+6,y-1/y*y-9y²-6y+9=(y-3)²2y+6=2(y+3)y²-9=(y+3)(y-3)最简公分母是2(y+3)(y-3)²(y+3)/(y

计算：[(y+1)/(y^2-4y+3)减去(y-2)/(y^2-6y+9)]除以(y-5)/(y-1)[(y+1)/(y^2-4y+3)减去(y-2)/(y^2-6y+9)]除以(y-5)/(y-1)=[(y+1)/(y-1)(y-3)减