Q7. Determine all positive integer $a$ such that the equation
$2x^2-210x+a=0$
has two prime roots, i.e both roots are prime numbers.
Q8. If $n$ and $n^3+2n^2+2n+4$ are both perfects squares, find $n$.
Q9. Let be given a triangle $ABC$ and points $D,M,N$ belong to $BC,AB,AC,$ respectively. Suppose that $MD$ is parallel to $AC$ and $ND$ is parallel to $AB$. If $S_{BMD}=9cm^2$,if $S_{DNC}=25cm^2$, compute $S_{AMN}$
Q10. fine the maximum value of
$M=\frac{x}{2x+y}+\frac{y}{2y+z}+\frac{z}{2z+x}, x,y,z>0$
Bài viết đã được chỉnh sửa nội dung bởi lehoangphuc1820: 15-03-2014 - 20:47