$\displaystyle u_{r}=4u_{r}+3\\u_{1}=6$

Test the answer by finding the value of $\displaystyle u_{4}$ in 2 different ways:

by substitution in your solution and by repeated evaluation of the equation.

by substitution I have found u2=27,u3=111 and u4=447

I'm wondering how to find these values by repeated evaluation of the equation?

Cheers

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