Moira borrowed $4,500 from her grandfather to pay for her first year of college. Three years later, she repaid the $4,500 along
with an interest of $243. What was the annual interest rate? Round your answer to one decimal place
1 answer:
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To graph it, just graph 
and 
and see where they intersect
I would like to solve it by using math and not graphing
if you don't want to see the math, just don't scroll down
the graphical meathod is above, first line, just read it
hmm
multiply both sides by -1
multiply both sides by
minus 1 from both sides and minus 6(3^x) from both sides
use u subsitution
we can rewrite it as
now factor
I mean use quadratic formula
for
so for 0=u^2-16u-1, a=1, b=-16, c=-1
remember that u=3^x so u>0
if we have u=8+√65, it's fine, but u=8-√65 is negative and not allowed
so therfor
if you take the log base 3 of both sides you get
if you use ln then
then
I would like to solve it by using math and not graphing
if you don't want to see the math, just don't scroll down
the graphical meathod is above, first line, just read it
hmm
multiply both sides by -1
multiply both sides by
minus 1 from both sides and minus 6(3^x) from both sides
use u subsitution
we can rewrite it as
now factor
I mean use quadratic formula
for
so for 0=u^2-16u-1, a=1, b=-16, c=-1
remember that u=3^x so u>0
if we have u=8+√65, it's fine, but u=8-√65 is negative and not allowed
so therfor
if you take the log base 3 of both sides you get
if you use ln then
then