Question 1186865
i believe this is:


your equation is, as far as i can tell,


3e^(-x) + 11 = 48


if so, subtract 11 from both sides of the equation to get:


3e^(-x) = 37


divide both sides of the equation by 3 to get:


e^(-x) = 37/3


take thre natural log of both sides of the equation to get:


ln(e^(-x) = ln(37/3)


since ln(e^(-x) = -x * ln(e) and, since ln(e) = 1, then ln(e^(-x) = -x.


your equation becomeds:


-x = ln(37/3)


solve for x to get:


x = -ln(37/3) = -2.512305624.


confirm by replacing x in the original equation to get:


3e^(-x) + 11 = 48 becomes 3e^(-2.512305624) + 11 = 48


evaluate to get 48 = 48, confirming the value of x is correct.


HOWEVER,


it is also possible that your equation is:


3e^(−x+11) = 48


without any parentheses, it's difficult to determine what you meant.


in this case, divide both sides of the equation by 3 to get:


e^(-x+11) = 16


take the natural log of both sides of the equation to get:


ln(e^(-x+11)) = ln(16)


since ln(e^(-x+11)) = (-x+11) * ln(e) which is equal to -x+11, your equation becomes:


-x + 11 = ln(16).


subtract 11 from both sides of the equation to get:


-x = ln(16) - 11.


multiply both sides of the equation by -1 to get:


x = -ln(16) + 11


solve for x to get:


x = 8.227411278.


confirm by replacing x in the original equation to get:


3e^(−x+11) = 48 becomes 3e^(−8.227411278+11) = 48


evaluate to get 48 = 48, confirming that the value of x is good.


if the original equation was 3e^(-x) + 11 = 48, then the solution is x = -2.512305624.


if the original equation was 3e^(−x+11) = 48, then the solution is x = 8.227411278.


i would have chosen the first option of 3e^−x+11 = 48 = 3e^(-x) + 11 = 48 because, without the parentheses, the equation becomes:
3 * e^(-x) + 11 = 48.
it then becomes:
(3 * e^(-x) + 11 = 48
subtract 11 from both sides to get:
3 * e^(-x) = 37
divide both sides by 3 to get:
e^(-x) = 37/3.
you then took the natural log of both sides to get:
-x = ln(37/3).
you then solve for x to get:
x = -ln(37/3).


these equations can be graphed.


the graph is shown below:


the red equation is y = 3 * e^(-x + 11).


the blue equation is y = 3 * e^(-x) + 11.


<img src = "http://theo.x10hosting.com/2021/102901.jpg" >