解方程组2x-y=7,5x 3y z=2,3x-4z=2
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|x-2|=7-|y-5|≥0解得4≤y≤12|x-2|=y-6≥0解得y≥6则,6≤y≤12|x-2|=7-|y-5|,|x-2|=y-6则,7-|y-5|=y-67-y+5=y-62y=18解得y
x3y+2x2y2+xy3=xy(x2+2xy+y2)=xy(x+y)2,∵x+y=5,∴(x+y)2=25,x2+y2+2xy=25,∵x2+y2=13,∴xy=6,∴xy(x+y)2=6×25=1
两边同乘5:30x-35y=-1030x-12y=-5.4上式减下式得:-23y=-4.6y=0.2将y代入原式得到x=-0.1化简为10x-11y=873x+y=82即:10x-11y=8733x+
{5(x+y)+3(x-y)=2{7(x+y)-3(x-y)=-6原方程组化简得﹛4x+y=1(1)2x+5y=-3(2)(1)×5得20x+5y=5(3)(3)-(2)得18x=8x=4/9代入(1
(2x4-4x3y-x2y2)-2(x4-2x3y-y3)+x2y2=2x4-4x3y-x2y2-2x4+4x3y+2y3+x2y2=2y3,因为化简的结果中不含x,所以原式的值与x值无关.
x-2y=5所以x=2y+5代入2x+7y=-14y+10+7y=-111y=-11所以y=-1x=2y+5=3
2x-3y=8①5x-7y=5②①*5得10x-15y=40③②*2得10x-14y=10④④-③得y=-30将y=-30带入①得x=-41
已知x+y=5,xy=3,代数式x3y-2x平方y平方+xy3=xy(x²-2xy+y²)=xy(x-y)²=3×[(x+y)²-4xy]=3×(25-12)=
8x+3y+2=0①6x+5y+7=0②①×5得40x+15y+10=0②×3得18x+15y+21=0两式相减:22x-11=0解得x=1/2代入①得4+3y+2=0解得y=-2所以方程组的解为x=
7-|y-5|=y-613-|y-5|=y若y<5,则8=0不成立故y≥5,则18=2y得y=9|x-2|=y-6=3x=5或-1结果为x=5,y=9或x=-1,y=9
x+y=4,xy=2后者平方后二式相加再加后者平方
令x/4=y/5=K,则x=4k,y=5k.所以12k-10k=10.解得K=5.则x=4k=20,y=5k=25.所以x=20,y=25
x3y+xy3=xy(x^2+y^2)=(√3-√2)(√3+√2)((√3-√2)^2)+(√3-√2)^2)=1*(3-2√6+2+3+2√6+2)=10
2x+3y=514x+21y=15-5x-7y=1-15x-21y=3两式相加14x-15x=15+3-x=18x=-183y=5-2x=5+2x183y=41y=41/3如果本题有什么不明白可以追问
3x-5y=7(1)4x+2y=5(2)解(1)×4得12x-20y=28(3)(2)×3得12x+6y=15(4)(3)-(4)得-26y=13y=-1/2把y=-1/2代入(2)得4x-1=54x
由②得:x=5-3y……③把③代人①得:5(5-3y)-2y=7,解得:y=18/17把y=18/17代人③得:x=5-54/17=31/17∴{x=31/17y=18/17
展开x^2-2y^2-xy=-5x^2-2y^2+xy=7所以x^2-2y^2=1xy=6上式除以下式,解分式方程x/y=3/2或-4/3(舍去)所以x^2=9y^2=4x=3y=2或x=-3y=-2
∵x-y=l,xy=2,∴x3y-2x2y2+xy3=xy(x2-2xy+y2)=xy(x-y)2=2×1=2.
a1=a2,b1=-b2,c1=c2a1=a2,b1=b2,c1不等于c2a1不等于a2,b1不等于b2,c1不等于c2
2x+3y=-k+2,①3x-2y=5k+3②2*①+3*②13x=13k+13所以x=k+1代入①y=-kx-y=2k+1=5k=2