x减2y=3和3x+4y=负1-搜答案-搜搜考试网

x^2-y^2=(x+y)(x-y)=-6(m-1/m)^2=m^2-2+1/m^2=16m^2+1/m^2=18(m^2+1/m^2)^2=m^4+2+1/m^4=324m^4+1/m^4=322

(x-y+x+y)/(x^2-y^2)*((x-y)^2/2x)=2x/(x-y)(x+y)*((x-y)^2/2x)=(x-y)/(x+y)x=根号3,y=负根号2原式=（根号3+根号2）/（根号3

x-y=44x+2y=-1x=y+44y+16+2y=-16y=-17y=-17/6x=7/6

再问：姐姐，图片看不清再答：再答：有问题还可以发给我哦，我尽全力解决再问：加个企鹅呗再答：杂加再问：在不再问：问你你问题再问：（2013河池）已知二次函数y=-x2+3x-35，当自变量x取m对应的函

x=-2;y=3x=-2;y=3x=-2;y=3x=-2;y=3x=-2;y=3

5X-3Y=212X-3Y=-1021-2得3X=12x=4将x=4带入Y=6X=4Y=6

利用复合函数求导法,很简单的.1、y'=-1/√[1-(1-2x)^2]*(-2)=2/√(4x-4x^2)=1/√(x-x^2)2、y'=1/cot(x/2)*[-csc^2(x/2)]*1/2=s

=3x平方y-2x平方y+6xy-3x平方y+xy=-2x平方y+7xy=-2*1*(-2)+7*(-1)*(-2)=4+14=18

再问：能有具体回答吗

y=负x分之3①y=负x+2②将①代入②,得-3/x=-x+2则-3=-x²+2x则x²-2x-3=0则(x-3)(x+1)=0则x=3或x=-1x=3时,y=-1x=-1时,y=

原式=4x²-y²-8x²+6xy-y²+2y²-6xy=-4x²=-4×(-1/4)²=-1/4

原式=-x-7y-7y/3+2(5x-4y)/3=-x-7y-7y/3+10x/3-8y/3=7x/3-12y当x=3,y=-2时原式=7+24=31

设原方程为ax+by=c（c≠0）,将两个解代入得a+2b=c①-7a-3b=c②①×7+②得11b=8c→b=8/11c①×3+②×2得-11a=5c→a=-5/11c所以原方程为-5/11cx+8

3(x+y)-4(x-y)=4(x+y)/2+(x-y)/6=1令a=x+y,b=x-y3a-4b=4(1)a/2+b/6=1则3a+b=6(2)(2)-(1)5b=2b=2/5a=(6-b)/3=2

3X+4Y=23X=2-4YX=(2-4Y)/3X-Y-1/7D

先化简原式=（2X-Y)(2X+Y)+(2X-Y)(Y-4X)+2Y(Y-3X)=4x"2-y"2-8x"2-y"2+6xy+2y"2-6xy=-4x"2=-1/4可以确定上式得值

5(2x平方y减3x)减2(4x减3x平方y),其中x=1/2,y=负1=10x²y-15x-8x+6x²y=16x²y-23x=16×(1/4)×(-1)-23×(1/

x+x^-1=4两边平方x²+2+x-=6x²+x-²=14所以原式=2*14=28x+y=2xy=-3则x²+y²=(x+y)²-2xy=

(x+y)/2+(x-y)/6=1x/2+x/6+y/2-y/6=12x/3+y/3=12x+y=3(1)3(x+y)-4(x-y)=43x+3y-4x+4y=4-x+7y=4(2)(1)+2*(2)