作业帮(3x 7y)(3x-7y)
来源：学生作业帮助网 编辑：作业帮 时间：2024/06/08 23:46:56
-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^
(3x+y)(3x-y)=9x²-3xy+3xy-y²=9x²-y²
2(y-x)²-7(x-y)+6(x-y)-3(y-x)²=-(y-x)²-(x-y)=-(x-y)²-(x-y)=-(x-y)[(x-y)+1]=(y-x)(
3分之7和7分之3
∵x+7y=y-3x∴x＝−32y∴x2−y2x2+y2=94x2− y294x2+y2=513故答案为513
3(X-Y)²-4(X-Y)+7(X-Y)-6(X-Y)²=(3-6)(X-Y)²+(-4+7)(X-Y)=-3(X-Y)²+3(X-Y)
4X-2Y=16P4X+7Y=7P-9Y=9PY=-P3X+7P=35X=3.5P17.5P=35P=2
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^
若(x-y)/(x+y)=3那么x-y=3(x+y)x-y=3x+3y故x=-2y所以(x+2y)/(6x-7y)=(-2y+2y)/(6*(-2y)-7y)=0如果不懂,请Hi我,祝学习愉快!
=3x/(x-4y)-(x+y)/(x-4y)-7y/(x-4y)=(3x-x-y-7y)/(x-4y)=(2x-8y)/(x-4y)=2(x-4y)/(x-4y)=2
7x加7y还是7x减7y
(-3x+7y)(-7y-3x)-(x-3y)(2x+3y)=(3x-7y)(3x+7y)+(3y-x)(3y+2x)后半部分相当于(x+a)(x+b)=x^2+(a+b)x+ab=9x^2-49y^
(x-y)(3x-7y)²-4(x-y)(x+y)²=(x-y)[(3x-7y)²-4(x+y)²]=(x-y)(3x-7y-2x-2y)(3x-7y+2x+2
1、(-7x^y)(2x^y-3xy^3+xy)=-14x^(2y)+21x^(y+1)y^3-7x^(y+1)y;2、((x-y)^6)/((y-x)^3)/(x-y)=-(x-y)^3/(x-y)
(3x-4y)(5x-4y)-(7x-8y)(6y-5x)=15x²-12xy-20xy+16y²-（42xy-35x²-48y²+40xy）=15x²
x-4y分之3x+4y-x分之x+y-x-4y分之7y=3x/(x-4y)-(x+y)/(x-4y)-7y/(x-4y)=(3x-x-y-7y)/(x-4y)=(2x-8y)/(x-4y)=2
(x-y)^7÷(y-x)^6+(-x-y)^3÷(x+y)^2=(x-y)^7÷(x-y)^6+[-(x+y)^3]÷(x+y)^2=(x-y)+[-(x+y)]=x-y-x-y=-2y
牛奶妹琪琪1：3x-5y=16①2x+7y=a-18②∵x,y互为相反数∴y=-x③把③代入①中,得3x-5×(-x)=163x+5x=168x=16x=2∴y=-2∴把x=2,y=-2代入②中,得2