Q85. Let $f$ be a differentiable function in the interval $( 0 , \infty )$ such that $f ( 1 ) = 1$ and $\lim _ { t \rightarrow x } \frac { t ^ { 2 } f ( x ) - x ^ { 2 } f ( t ) } { t - x } = 1$ for each $x > 0$. Then $2 f ( 2 ) + 3 f ( 3 )$ is equal to $\_\_\_\_$\\