=x^2 - 2*1/2x + 1/4 + 1/2
=x^2 - 2*1/2x + (1/2)2 +1/2
=(x-1/2)2 + 1/2
vì (x-1/2)2 lon hon hoac bang 0
suy ra (x-1/2)2 +1/2 lon hon 0
mình rât cảm ơn bạn Nguyen Thi Hai Yen
cho da thuc f(x)= -2+x^4+2x^2-3x^3+4x^4-5x^4+3x^3+3 chung minh rang da thuc f(x) ko co nghiem tai moi gia tri cua x
chung minh rang bieu thuc sau luon luon co gia tri am voi moi gia tri cua bien: -5-(x-1)(x+2)
chung minh rang bieu thuc 4x(x+y)(x+y+z)(x+y) y^2x^2 luon luon khong am voi moi gia tri cua x,y va z
chung to rang phuong trinh
6x=3 ( 2x + 2) - 6
nghiem dung voi moi gia tri cua x
chung minh P=x^4 - 2x^3 + 2x^2 - 2x + 1 lon hon hoac = 0 voi moi gia tri cua x
cho D =[1/x-1 - 2/x3-x2+x-1] : (1-x/x2+1)
a) rut gon D
b) chung minh rang D>0 voi moi gia tri cua x de D co nghia
Chung minh bieu thuc sau luon co gia tri duong voi moi gia tri cua x
B=x4-2x3+2x2-4x2-4x+5
Tim gia tri nho nhat A=x2-2x
Tim gia tri lon nhat B=-x2+4x-5
Chung minh rang: x4+6x3+11x2+6x chia het cho 24 voi moi x thuoc N
chung minh cac hang dang thuc sau luon co gia tri duong voi moi gia tri cua bien
4)D=x^2 -2x+y^2+4y+6
5)P=(15x - 1)^2+3(7x+3)(x+1) -(x^2 -73)
