Cho ba don thuc:\(M=-5xy\),\(N=11xy^2\),\(P=\frac{7}{5}x^2y^3\).Chung minh rang ba don thuc nay khong the cung co gia tri duong.
Cho 3 don thuc \(\frac{5}{3}x^2y^5z^3;\frac{-2}{5}x^3yzt^2;\frac{3}{7}x^{15}y^4z^2\)
Trong do cac bien x, y, z, t khac 0
Chung minh rang trong 3 don thuc da cho co it nhat 1 don thuc gia tri am.
cho cac da thuc a=-1/2x^2yz^2 b=-3/4xy^2z^2 c=x^3y cmr cac da thuc a b c khong cung nhan gia tri am
cho bieu thuc 4x. Hay ly luan de chung to bieu thuc do khong co gia tri lon nhat khong co gia tri nho nhat
cho x,y,z la 3 so thuc tuy y thoa man x+y+z=0 va -1< x<1,-1<y<1,-1<z<1.chung minh rang da thuc x^2+y^4+z^6 co gia tri khong lon hon 2
Chung minh da thuc Q(x) = x^4 + 3x^2 + 1 khong co nghiem voi moi gia tri cua x
cho 3 đa thuc
a) x^20+Y^10-x^10y^20
b)x^10-y^10-3x^10y^10
c)-x^20+y^20+4x^10y^10
chung to tai moi gia tri cua x va y thi 3 da thuc khong dong thoi nhan gia tri am
bai 1: Cho cac don thuc A=-4/9x^3y va B= 3/8 x^5y^3. Tim cac cap gia tri (x;y)de A,B cung gia tri am
bai 2: viet don thuc B=64xy^12 duoi dang luy thua cua 1 don thuc voi so mu khac 1
bai 3: cho A=8x^5y^3; B=-3x^6y^3; C=-6x^7y^2. CM: Ax^2+Bx+C>0
a)Cho vi du ve 1 don thuc ,1 da thuc nhung khong phai la don thuc ,2 don thuc dong dang voi nhau ,da thuc 1 bien
b)Hay viet 1 don thuc dong dang voi don thuc don thuc xy\(^3\) sao cho tai x=-1 y=2 gia tri cua don thuc do la so nguyen duong nho hon 10