3x² 4y²-12x-8y 16=0-搜答案-搜狗做题网

(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

X1~N(0,16)所以1/4X1~N(0,1),对X2……X9一样的那么(1/4X1)^2+(1/4X2)^2……+(1/4X9)^2~X^2(9)这里X是卡方分布,打不出来同理：(1/3Y1)~N

写清楚点点比如说前面是X/X还是X/(X-Y)打上括号分段这样才能清楚的做

(x,y),Z=x^2+y^2+(X+2y-16)^2/5,化简后,这方法最烦最好联想到三角形,圆的知识

【x-y-(x-y分之4y平方)】【x+y-(x+y分之4x平方)】除以【3(x+y)-x-y分之8xy】=（x-y-x+4y)(x+y-x-4x/y)/(3x+3y-x-8x)=3y*(y-4x/y

-x^y^7+y^8)(这里有问题,x的几次方?再问：就是一次方再答：(x^8-x^7y+x^5y^3-x^4y^4+x^3y^5-xy^7+y^8)(x^2+xy+y^2)=（x^8-x^7y+x^

根号(x+y-8)+根号(8-x-y)=根号(3x-y-4)+根号(x-2y+7),根据二次根式有意义得：X+Y-8≥0,8-X-Y≥0,∴X+Y≥8,X+Y≤8,∴X+Y=8,左边为0,右边两个非负

解6x³y^6÷(1/2)y³÷(-3x²y)-(12x^4y^6-8x²y^4-16x³y^5)÷4x²y³=12x³

(1)x+y+z=6①3x-y+2z=12②x-y-3z=-4③①+②4x+3z=18④②-③2x+5z=16⑤⑤×24x+10z=32⑥⑥-④7z=14解得z=2代入⑤2x+5×2＝16解得x=3将

2x-y/x+3y=2得x+3y/2x-y=1/24x-2y/x+3y减4x+12y除以2x-y=2(2x-y)/x+3y-4(x+3y)/2x-y=2乘以2-4乖以1/2=4-2=2

答案是2.4x-2y/x+3y=(2x-y/x+3y)乘以2=4,4x+12y/2x-y=(x+3y/2x-y)乘以4=1/2x4=2,所以代数式等于4-2=2.

(x+y)-(2x+y/2)-(3x+y/6)-(4x+y/12)-(5x+y/20)-……-(10x+y/90)=x-2x-3x-4x-..-10x+y*(1-1/2-1/6-1/12-..1/90

解题思路：对于这种等式一定可以化成平方相加的形式，这里面要使用到完全平方公式。解题过程：

(x-y)^8

y=-3x的平方+12x-3=-3(x²-4x)-3=-3(x-2)²+9y=4x的平方-24x+26=4(x²-6x)+26=4(x-3)²-10y=2x的平

1/(x-y)-1/(x+y)-2y/(x^2+y^2)-4y^3/(x^4+y^4)-8y^7/(x^8+y^8)=【（x+y)-(x-y)】/(x-y)(x+y)-2y/(x^2+y^2)-4y^

1.（（y+2x)(-2x+y)+4(x+2y)^2)/3y=(y^2-4x^2+4x^2+16xy+16y^2)/3y=(17y^2+16xy)/3y=17y/3+16x/32.（2(x-y)^3-

解9y=3x-(x-1)2x-9y+1=0①4(x+y)-(2x+4)=8y2x-4y-4=0②②-①得：5y-5=0∴y=1将y=1代入①得：2x-9+1=0∴x=4∴方程的解为：x=4,y=1

(3x-4y)(5x-4y)-(7x-8y)(6y-5x)=15x²-12xy-20xy+16y²-（42xy-35x²-48y²+40xy）=15x²