Hello there! I was just wondering if someone could kindly show me how to do the following questions:
1) 4^x + 6(4^-x) = 5
2) The half-life of a certain substance is 3.6 days. How long will it take for 20g of the substance to decay to 7g?
-The only equation I know of is y = ab^x but I'm not sure what to put where, thank you!!