(x+y)2-(x-y)2 = (x2 + 2xy + y2) - (x2-2xy+y2)
= x2 + 2xy + y2 - x2 + 2xy - y2 = 4xy
(x+y)2-(x-y)2 = (x2 + 2xy + y2) - (x2-2xy+y2)
= x2 + 2xy + y2 - x2 + 2xy - y2 = 4xy
4x(x+y)(x+y+z)(x+z)+y^2z^2 chung minh luon luon >= 0 voi moi x,y,z
moi nguoi ghi ro chi tiet tung cach lam nhja ^^ khong skip buoc nao
tks mn a
giup minh bai nay vs
a)-3x^4y+6x^3y-3x^2y
b)3x(x-2y)+6y(2y-x)
c)8x^2+4xy-2ax-ay
e)x^3-y^2-2yz-z^2
d)x^2-2xy+y^2-m^2+2m-n^2
g)a^2-10a+25-y^2-4yz-4z^2
ban nao lam dc minh tick
Bài 1:
cho x,y>=1 CMR: \(\frac{-1}{x^2+1}+\frac{1}{xy+1}=<\frac{1}{y^2+1}-\frac{1}{xy+1}\)
cac bai oi giup minh bai BDT nay kho qua. dau nam giup minh di. lay may nao. lam on di
1) Phan tich da thuc sau thanh nhan tu: x2-x-2008.2009
2) Chung minh rang voi moi x,y,z ta luon co: x2+4y2+z2>=2x+12y+4z
3) Cho a-b=4. Tinh gia tri cua bieu thuc: a3-12ab-b3
cac ban lam duoc cau nao thi giup mik nha. mik dang can gap lam
lam tính chia
[ 3(x-y)^4+2(x-y)^3-5(x-y)^2]: (x-y)^2
lam tính chia
[ 3(x-y)^4+2(x-y)^3-5(x-y)^2]: (x-y)^2
ai làm bài giúp em với ạ
Tính GTBT cho x+y=5
a, A=3x2-2x+3y2-2y+6xy-100
b,B=x3+y3-2x2-2y2+3xy.(x+y)-4xy+3.(x+y)+10
c, Cho x+y=3, x2+y2=5
Tính x3+y3
Giup minh nha. ma minh do ai lam dc bai nay lam dc cho tien luon. ns thay do
a)x^3.(z-y^2)+y^3.(x-z^2)+z^z^3.(y-x^2)+xyz.(xyz-1)
Cac ban lam dj mk tick cho!!
1 ,lam tinh nhan :
a,\(x^2\left[5x^3-x-\frac{1}{2}\right]\)
b,\(\left[3xy-x^2+y\right]\frac{2}{3}x^2y\)
c[,\(4x^3-5xy+2x\)]\(\left[-\frac{1}{2}xy\right]\)
cac bn nao thong mjk thi tl lun nha