bai nay de bai hoi nham mot chut .no luon duong bang 0 the nao dk her
Bai nay thi phan tich thanh nhan tu? la xong chu' co gi dau
2x^4 + 5x^2 + 3 = (2x^2 + 3)(x^2 + 1)
vi' 2x^2 + 3 > 0 voi moi x'
x^2 + 1 > 0 voi moi x'
==> 2x^4 + 5x2 + 3 > 0 vi moi x
de~ the' mak