# Math Help - make t subject

1. ## make t subject

i need to make t subject.

any1 help?

2. $A=A_0 e^{-\lambda t}$

$\frac{A}{A_0}= e^{-\lambda t}$

$\ln\frac{A}{A_0}= -\lambda t$

$t= \frac{-1}{\lambda}\ln\frac{A}{A_0}$

3. i cant seem to get the correct answer t=-4.76 x 10^-5

A= 0.005
A_0= 0.005
{\lambda= 0.1}

4. $t= \frac{-1}{\lambda}\ln\left(\frac{A}{A_0}\right) = \frac{-1}{0.1}\ln\left(\frac{0.005}{0.005}\right) = 0$

Is $A = A_0$ ?

5. The values of A, A0 and λ are 0.005, 0.005 and 0.1. Find the value of t?