已知x-y x y=4,求代数式3x-3y x y x y x-y的值
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代数式x²加x+3等于7x²+x+3=7x²+x=4则代数式3x²+3x-4=3(x²+x)-4=3*4-4=12-4=8
2x³+4x²+3=2x(x²+x-1)+2x²+2x+3=2x²+2x+3=2(x²+x-1)+5=5明教为您解答,请点击[满意答案];如
x+x^(-1)=3(x+x^(-1))^2=3^2=9x^2+x^(-2)=7x^4+x^(-4)=47
x^2+x-1=0x^2+x=12x^3+4x^2+3=2x^3+2x^2+2x^2+3=2x(x^2+x)+2x^2+3=2x*1+2x^2+3=2(x^2+x)+3=2*1+3=5
∵正数x,y满足2x+y-3=0,∴3=2x+y.∴x+2yxy=13(2x+y)(1y+2x)=13(5+2xy+2yx)≥13(5+22xy•2yx)=3,当且仅当x=y=1时取等号.则x+2yx
2x+3y=53y=5-2xy=(5-2x)/33x^2+12xy+y^2=3x^2+12x(5-2x)/3+(5-2x)^2/9x=4时=48-48+1=1
y=3x/5原式=x/(x+3x/5)+(3x/5)/[x-3x/5]-(9x^3/25)/(x^3-9x^3/25)=8/3-3/2-9/16=29/48
∵x+y=3,∴原式=3×32-43+2×3-3=2823.
(1)XxX+yxy=(x+y)^2-2xy=4^2+2*12=16+28=44(2)XxXxy+Xxyxy=xy*(x+y)=4*(-12)=-48不懂可追问,有帮助请采纳,谢谢!
x²+x-1=0x²+x=12x³+4x²+3=2x³+2x²+2x²+3=2x(x²+x)+2x²+3=2x
可以采用降次法∵x²+x-1=0∴x²=1-x所以2x³+4x²+3=2x(1-x)+4x²+3=2x²-2x+3=2(1-x)+2x+3=
=3-2(x+2y)=3-2x3=3-6=-3
(x+1)(x-2)(x+3)(x-4)+16=0,(x²-x-2)(x²-x-12)+16=0(x²-x)²-14(x²-x)+24+16=0(x&
|3-y|+|x+y|=0,且|3-y|≥0,|x+y|≥0,所以3-y=0,x+y=0,所以y=3,x=-3.所以x+yxy=-3+3-3×3=0-9=0.答:x+yxy的值为0.
∵3x2-4x+6=9,∴x2-43x+2=3,即x2-43x=1∴x2-43x+6=1+6=7.再问:看不懂?
x^4+4x^3-4x-4=x^2*(x^2+4x+4)-3x^2-x^2-4x-4=x^2(x+2)^2-3x^2-(x+2)^2x+2=√3代入x^2(x+2)^2-3x^2=0原式=(x+2)^
x/y=3/2则2x=3y带进去就变成6y-9y/(3y+3y)=-1/2y感觉怪怪的.一般都是转换下形式然后带进去这题怎么没一般项--或者直接将x=3y=2带进去
x²+x-1=0x²+x=12x³+4x²+3=2x³+2x²+2x²+3=2x(x²+x)+2x²+3=2x
6x²-2x=2所以3x²-x=13x²-x+4=5
X*2+Y*2=(X+Y)*2__-2XY;因为X+Y=3;XY=2;所以X*2+Y*2=9-4=5.