Quote by shounakbhatta
Sorry,
F=G.m1.m2/r^2
Can it be written:
F=G.m.m/r^2.

Sometimes when writing the force as a vector expression a minus sign is used to indicate that it's an attractive force:
[tex]\vec{F} =  \frac{G m_1 m_2}{r^2} \hat{r}[/tex]
Where [itex]\vec{r}[/itex] is the position vector of m_2 with respect to m_1 and [itex]\vec{F}[/itex] is the gravitational force on m_2 due to m_1.
See:
Vector form