Question

pls ajutati ma cat mai repedeee

Answer 1

$\bf c.\it\ =4^{15}-3(4+4^2+4^3+\ ...\ +4^{14})=4^{15}-3\cdot4\cdot\dfrac{4^{14-1}}{4-1}=\\ \\ \\ =4^{15}-4(4^{14}-1)=4^{15}-4^{15}+4=4$