Answer:
an = -6n + 5.
Step-by-step explanation:
This is an arithmetic sequence with first term a1 = -1 and common difference d = -6
an = a1 + d(n-1)
an = -1 + -6(n - 1)
an = -1 -6n + 6
an = -6n + 5.
The general way to work this out is to solve the general expression for
the remaining quantity versus half-life, using logarithms. But that's not
necessary with these numbers.
Look at the numbers:
-- 3 mg is 1/4 of 12 mg.
-- 1/4 is the product of (1/2) x (1/2).
-- So the 3 mg is what's left of 12 mg after 2 half-lives.
The 26 minutes must be two half-lives.
-- The half-life of that substance is 26/2 = <em>13 minutes</em>.
Go Maggie !
The y-intercept would be (0,8) because the last number on the equation, aka the c value, is you y-intercept.
