8x 7y 14*(10-x-y)=101

x^2+y^2-8x-6y+21=0配方,有：x^2-8x+16+y^2-6y+9=4(x-4)^2+(y-3)^2=4这是一个以(4,3)为圆心,2为半径的圆令x-4=2sinay-3=2cosa(

(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=4x-2y-z-5x[6y-(x+y)]+x-(3y-10z)=4x-2y-z-30xy+5x²+5xy+x-3

二式乘4得三式,三式减一式得：17X=14得X=14/17将X代入一式,得Y=16/17

2y-7x=8①3x-8y-10=0②①*4+②,-28x+3x-10=32,x=-42/25代入①,2y-7*(-42/25)=8,y=-47/25

(4.5*10^5)(2*10^3)(3*10^4)=（4.5×2×3）×10^(5+3+4)=27×10¹²=2.7×10¹³2x^2y(-8y^2)+4x^

-3(2x-y)-{7x-[6x+2y-(10x-8y)]-x-2(3x-4y)}=-6x+3y-7x+(6x+2y-10x+8y)+x+6x-8y=-13x+3y-4x+10y+7x-8y=-10x

2x-7y=8①3x-8y=10②①乘3得到6x-21y=24③②乘2得到6x-16y=20④③－④得－5y＝4y=－5分之4将y=－5分之4代入③得x=5分之6希望对你有帮助~望采纳,O(∩_∩)O

2x+y+x=10(1)x+2y+z=-6(2)x+y+2z=8(3)(1)+(2)+(3)4x+4y+4z=12x+y+z=3(4)(1)-(4),x=7(2)-(4),y=-9(3)-(4),z=

1、3y=2x①3x+4y+805=0②由①得x=1.5y,带入②4.5y+4y=-805y=-1610/17x=-2415/17……再问：再解一道(a+b-c)^3x(c-b-a)^2(-a-b+c

2x+y+z=10(1)x+2y+z=-6(2)x+y+z=8(3)(2)-(3):y=-14(4)(1)-(2):x-y=16(5)把（4）代入（5）：x+14=16x=2(6)把（4）和（6）代入

-8(2x-y)-{7x-[6x+2y-(10x-8y)]}=-16x+8y-[7x-(6x+2y-10x+8y)]=-16x+8y-(7x-6x-2y+10x-8y)=-16x+8y-7x+6x+2

x^2+y^2-8x-10y+41=0x^2-8x+16+y^2-10y+25=0(x-4)^2+(y-5)^2=0所以x=4,y=5x/y+y/x＝4/5+5/4=0.8+1.25=2.05

x^2+y^2-8x+10y+41=0(x-4)^2+(y+5)^2=0x=4,y=-5x+y=-1(x+y)^2013=-1

(X+2)(X+5)(X-4)(X+2)(y-3)(y-4)(x+9)(x-2)

当2x+y＞0时就变为3x+y=10,x-2y=8解得x=4,y=-2满足2x+y＞0当2x+y＜0时变为-x-y=10,x-2y=8y=-6,x=-4满足2x+y＜0∴两组解为x=4,y=-2或x=

-3(2x-y)-{7x-〔6x+2y-（10x-8y）〕-x-2(3x-4y)}=-6x+3y-{7x-6x-2y+10x-8y-x-6x+8y}=-6x+3y-(4x-2y)=-10x+5y由(x

-3(2x-y)-｛7x-〔6x+2x-(10x-8y)〕-x-2(3x-4y)｝=-6x+3y-｛7x-〔8x-10x+8y)〕-x-6x+8y｝=-6x+3y-｛7x-〔-2x+8y)〕-7x+8

等于.-3y-10x

什么意思?再问：tangram_guid_1358503626031再答：1：2x+3y=7,3x-5y=1;x=2y=12:3x+5y=5,3x-4y=23;x=5y=-23:3x+5y=5,3x-

很累-3x-2y