00:01
A radioactive substance decays from 100 milligrams to 50 milligrams in 35 hours.
00:07
Now, if we have the same substance, we want to know how many milligrams we have left of that substance after 54 hours.
00:15
So we also know that the equation to set up an exponential equation, it can be represented by f of x is equal to a times b to the x, where a is the principal amount of the substance that you have.
00:27
So in our case, 100 milligrams.
00:29
And x is the time and hours, so in this case 35 hours, about the substance is decaying, and your f of x is equal to the final amount, so 50 milligrams.
00:43
So using all this information, we can solve for the rate of decay, and then we can find out how much the substance would decay in 54 hours, how much would be let.
00:53
So we'll start off by setting this up as f of 35, which we know is equal to 50.
00:58
So we have 50 is equal to, sorry, 50 is equal to, a is equal to 100, 100 times b to the 35, because our x is 35 hours.
01:14
So now if we wanted to solve this, we would first divide both sides by 100...