1.How do I graph the function f(x)=5(o.5)^{-x} and its reflection across the y-axis on the same axes, and give the x-intercept of the reflection. How do I prove thata^x=e^{x lna}

2.How long will it take before twenty percent of our 1,000-gram sample of uranium-235 has decayed?

The decay equation is A(t)=A_0e^{Kt}, where t is the time for the decay, andKis the characteristic of the material. SupposeTis the time it takes for half of the unstable material in a sample of a radioactive substance to decay, called its half-life. Prove thatK= \frac{ln0.5}{T}.

What isTfor the uranium-235?