# precalculus

posted by .

My book tells me to solve each exponential equation. I am given a lot of problems such as
6^x+1 = 4^2x-1
where I use In in the problem to help get my answer. However, in the same section, the book starts giving me problems such as
3(2)^x-2 +1=100

and .05(1.15)^x =5 etc.
Where I apparently have to use log in the equations instead of using In like I did in all the other problems. Why is this? Like, how will I know weather to use In or log to find my answer? Is there a reason why you use log instead?

• precalculus -

It makes no difference if you use ln or log unless the exercise tells you to. If you are allowed a calculator then it makes no difference.
In the example above:
3*2^(x-2)+1=100 3*2^(x-2)=99 2^(x-2)=33
If we use ln we get: ln2^(x-2)=ln33
(x-2)ln2=ln33 x= 2+ln33/ln2=7.044
If we used log with base 2 we would get: x-2=log(base2)33 so x= 2+log(base2)33 =7.044
No difference!

## Similar Questions

1. ### DRWLS CAN YOU ANSWER

How do i solve inequalitites with three variables. I still can't figure it outplease help. x+y=1 y-z=-3 2x+3y+z=1 THE ANSWERS ARE3,-2,1 HOW DID THEY GET THAT ANSWER. This can be solved a number of ways. 1) subsitition 2) determinants …
2. ### Algebra

x/(x-3)-4-(2x-5)/(x+2) If the problem is this: x/(x - 3) - 4 - (3x - 5)/(x + 2) ...find a common denominator to start. The common denominator is (x - 3)(x + 2), then convert each term using the common denominator. Here's a start: [x(x …
3. ### Algebra

The answer in the book however says -(5x^2-17x-9)/(x-3)(x+2) so I don't know what I am doing wrong, can you take me step by step through the problem. I have a lot of problems, but I think once I understand what I am doing wrong with …
4. ### geometry

I am currently in a section of my geometry book titled Applying Properties of Similar Triangles. This is a very easy section but there is on problem where I cannot figure out (forgot) the next step. 1. z-4 12 --- = --- z/2 10 2.(z-4)10 …
5. ### Precalculus problems check?

Did I do these two problems right? P(1-sqrt2) = 8x - 4x^2 P(1-sqrt2)= -4 P(2/x)= 8x - 4x^2 P(2/x) = x-1 I think when the answers are plugged back in, the equation is supposed to equal zero, but I don't get this; however, I always redo
6. ### Algebra

I was given this answers to a problems I solved but I do not understand what she means hope you can help. Before attempting to solve this quadratic equation, determine how many solutions there will be for this quadratic equation. Explain …
7. ### Algebra

I was given this answers to a problems I solved but I do not understand what she means hope you can help. Before attempting to solve this quadratic equation, determine how many solutions there will be for this quadratic equation. Explain …
8. ### English

I'm worried about my math. 1. Why don't you buy a math self- teaching book and solve math problems a lot. 2. Why don't you buy a math self-study book and solve math problems a lot. 3. Why don't you go to a math academy and study math …
9. ### General Physics II

Hi, this is about thin film interference in ray optics. My book presents two similar problems, but somehow uses different paths for the same variable. I'll list out the given variables: --Problem A-- n1 < nf > n2, delta phase …
10. ### Ray Optics

Hi, this is about thin film interference in ray optics. My book presents two similar problems, but somehow uses different paths for the same variable. I'll list out the given variables: --Problem A-- n1 < nf > n2, delta phase …

More Similar Questions