b, Ta co: \(x^3+xy^2-x^2y-y^3+3\)
\(=\left(x^3-y^3\right)+\left(xy^2-x^2y\right)+3\)
\(=\left(x-y\right)^3+3xy\left(x-y\right)-xy\left(x-y\right)+3\)
= 3 ( vì x-y = 0)
tinh gia tri bieu thuc:
a,3x^4+5x^2y^2+2y^4+2y^2 biet rang x^2+y^2=1
tinh gia tri bieu thuc:
a,3x^4+5x^2y^2+2y^4+2y^2 biet rang x^2+y^2=1
tinh gia tri bieu thuc:
a,3x^4+5x^2y^2+2y^4+2y^2 biet rang x^2+y^2=1
tinh gia tri cua bieu thuc:
3x^4+5x^2y^2+2y^4+2y^2 biet rang x^2+y^2=1
tinh gia tri cua cac bieu thuc sau:
3x^4+5x^2y^2+2y^4+2y^2 biet rang x^2+y^2=1
tinh gia tri cac bieu thuc sau:3x^4+5x^2y^2+2y^4+2y^2biet rang x^2+y^2=1
tinh gia tri bieu thuc A tai x=-1/2; y=4;z=6
A=x^2y+(-x^3-3xyz)-(4-3xyz)+(-14^15)^0
6.a) tim 2 so x, ybik 7x=2y va x-y=16
b)so sanh a,b,c bik a/b=b/c=c/a
c)tim cac so a,b,cbik a/2=b/3=c/4 va a+2b-c=-20
d)cho x/2=y/5=z/7 tinh gia tri bieu thuc A=x-y+z/x+2y-z
e)cho 3x-2y/4=2z-4x/3=4y-3z/2.CMR x/2=y/3=z/4
f)cho a,b,c la cac so huu ti khac sao choa+b-c/c=a-b+c/b=-a+b+c/a
tinh gia tri bang so cua 1 bieu thuc m=(a+b)(b+c)(c+a)/abc
g)cho x/a=y/b=z/c CMRbz-cy/a=cx-az/b=ay-bx/c
Tìm đa thức M , biết :
a) \(M-\left(\frac{1}{2}x^2y-5xy^2+x^3-y^3\right)=\frac{3}{4}xy^2-2x^2y+\)\(2y^3-\frac{1}{3}x^3\)
b)\(\left(-\frac{1}{3}x^3y^3+5x^2y^2-\frac{5}{2}xy\right)-M=xy-\frac{1}{6}x^3y^3-3x^2y^2\)
c)\(\left(\frac{2}{7}xy^4-5x^5+7x^2y^3-3\right)+M=0\)
