Question

Someone help me please I don't know how to do this ! :(

Answer 1

$4^{x+1}=21\\ x+1=\log_421\\ x=\log_421-1\\ x=\log_421-\log_44\\ x=\log_4\dfrac{21}{4}\\ x=\dfrac{\ln \dfrac{21}{4}}{\ln 4}\approx 1.1962$