( 7.5 )^3 + 1 ( 7.5 )^2 - 6.5 is equal to = ?

Answer: Option D

$$\begin{array}{rl}& \text{According to question,}\\ & \Rightarrow \frac{{\left(7.5\right)}^3+1}{{\left(7.5\right)}^2-6.5}\\ & \left[\therefore a^3+b^3=\left(a+b\right)\left(a^2+b^2-ab\right)\right]\\ & \Rightarrow \frac{\left(7.5+1\right)\left[{\left(7.5\right)}^2+1-7.5\times 1\right]}{{\left(7.5\right)}^2-7.5\times 1+1^2}\\ & \Rightarrow 8.5\end{array}$$