[tex]\begin{gathered} T\text{he rate of increasing the height of tree is }\frac{3\text{ cm}}{2\text{ days}} \\ \text{The number of days in a week is 7.} \\ So,\text{ total number of days in 2 weeks is 2}\times7=14\text{ days} \\ \text{The increase in height of tree in 2 days is as follows:} \\ 14\text{ days}\times\frac{3\text{ cm}}{2\text{ days}}=21\text{ cm} \end{gathered}[/tex]
Thus, the answer is 21 cm.
