已知x加y等于负3
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y=k/(x+2)把x=-1,y=3代入上式,3=k/(-1+2)k=3=3/(x+2)
x²-y²=6y=-x+3代入x²-(-x+3)²=6x²-x²+6x-9=66x=15所以x=5/2y=-x+3=1/2
xy=-2x-y=-3-6xy-10y+10x=12-10(y-x)=12+30=42
f(x)=-x³+ax²+bx+cf'(x)=-3x²+2ax+b因为f(x)在(1,-2)处的切线为y=-3x+1所以f(1)=-1+a+b+c=-2(1)f'(-1)
5x+y=32x+3y=-91式*3-2式x=18/13y=-51/13xy=-918/169
xy分之x加y等于2∴x+y=2xy3x减5xy加3y分之负x加3xy减y=[-(x+y)+3xy]/[3(x+y)-5xy]=(-2xy+3xy)/(6xy-5xy)=xy/(xy)=1
x-y=-2①x+y=1②把①+②得x-y+x+y=-2+12x=-1x=-1/2把x=-1/2代入②得(-1/2)+y=1y=1-(-1/2)=3/2∴x=-1/2,y=3/2即x=-0.5,y=1
解y=ax³+bx+3x=3时,a×3³+3b+3=-7∴a×3³+3b=-10当x=-3时a×(-3)³-3b+3=-(a×3³+3b)+3=10+
(x-y)²=(x+y)²-4xy=25-12=13
3-(x-2y)=3+2=5再问:太给力了,你的回答完美解决了我的问题!
x²=25x=±5y³=-27y=-3所以x+y=-5-3=-8或x+y=5-3=2
解由一次函数为y=-3x+6当x>2即3x>6即-3x<-6即-3x+6<-6+6即-3x+6<0即y<0
1.x=-3-y,5x+5y-2=5(-3-y)+5y-2=-172.(1)2x平方=7+3x,原式=2(7+3x)-6x+5=19(2)原式=1/3(7+3x)-x+5/3=123.D(题目输入有歧
x-3y=-35-x+3y=5-(x-3y)=5-(-3)=8
已知xy/(x+y)=2,求:(3x-5xy+3y)/(-x+3xy-y)xy/(x+y)=2得:xy=2(x+y)(3x-5xy+3y)/(-x+3xy-y)=(3x-9xy+3y+4xy)/(-x
x的平方y加上x乘y平方=(x+y)xy=-18
根据(x+y)2=x2+y2+2xy,可得x2+y2=13
∵x的平方加xy等于负5,xy加y的平方等于9∴x的平方减y的平方=(x²+xy)-(xy+y²)=-5-9=-142x的平方加3xy加y的平方=2(x²+xy)+(xy