4x-2y=4和2x y=2解方程-搜答案-搜搜做题作业网

原式=2xy(x²+2xy+y²)=2xy(x+y)²=2*2*4²=64

x方-y方=x²-xy+xy-y²=(x²-xy)+(xy-y²)=60+40=1002x方-5xy+3y方=2x²-2xy-3xy+3y²

5X方—3XY—4Y方—11XY—7X方+2Y方=-2x²-2y²-14xy=-2×7-14×（-2）=-14+28=14

因为3x方+xy-2y方=0,即（x+y)(3x-2y)=0,而x+y≠0,所以3x-2y=0原式=[（x+y)^2-4xy]/[(x+3y)(x-y)/(x+3y)(x-3y)=(x-3y)/(x+

x方+4y方=4xyx²-4xy+4y²=0(x-2y)²=0x=2yx+2y/x=(2y+2y)/(2y)=2

即(3x-4y)(x+y)=03x=4y或x=-y若3x=4yy=3x/4则y²=9x²/16,xy=3x²/4原式=(3x²/4-3x²)/(9x&

∵y/x=3∴y=3x∴原式=(3x²-12x²+18x²)/（6x²-3x*3x+7*9x²)=9x²/(60x²)=3/20

∵x^2+y^2-2x+4y+5=0配方：∴(x-1)^2+(y+2)^2=0那么x-1=0且y+2=0所以x=1,y=-2∴(x^4-y^4)/(2x^2+xy-y^2)*（2x-y)/(xy-y^

x²+2xy+4y²+x²y²+1=8xy(x²-4xy+4y²)+(x²y²-2xy+1)=0(x-2y)²

2(x+y)方-2=50-2=48

(2x^4)y³－x³y^4=(x³y³)(2x－y)=(xy)³(2x－y)=4³×(1/16)=4

∵y分之x=5∴x=5y(4x²-5xy-6y²)分之(x²-2xy+3y²)=(100y²-25y²-6y²)分之(25y

(3x+4y)+(4x+3y)=7(x+y)=-16=8mm=-2m^2+2m+1=1m^2+1/m^2=17/4

（x-2y）（x方-2xy+4y方）=x³-2x²y+4xy²-2x²y+4xy²-8y³=x³-4x²y+8xy

∵|x-2a|+(y+3)²=0∴x=2a,y=-3∵A=2x²-3xy+y²-x+2y=8a²+16a+3,B=4x²-6xy+2y²+3

这个不是直接算x、y而是对多项式进行变形；5x方-3xy-4y方-11xy-7x方+2y方=（5-7）x²+（-3-11）xy+(-4+2)y²=-2x²-14xy-2y

∵x²+y²+6x-2y+10=0∴(x²+6x+9)+(y²-2y+1)=0即(x+3)²+(y-1)²=0由平方的非负性可得(x+3)&

基本不等式5分之2根号10

4x方-4xy+y方-4x+2y-15=(2x-y)^2-2(2x-y)-15=(2x-y-5)*(2x-y+3)4x方y方-5x方y方-9y方题目弄错了吧,应该是这样的吧=4x^2y^2-5xy-9