Expression evaluation I have encountered this expression and I cannot evaluate to the desired result on the right side
$$3\cdot4^{k+1}+4^{k+1}-64 = 4^{k+2}-64$$

$$3\cdot4^{k+1}+4^{k+1}-64 = (4^{k+1}\cdot(3+1)) - 64 =(4^{k+1}\cdot 4^{1}) - 64 = 4^{k+2} - 64 $$
