30 = 10 ln(x+3)....what is x? HELP!?

Question

How do you arrive at x? What laws/properties do you use to get there? Please...if you don't know what you r talking about....don't answer....THANK YOU!

Answer 1

THE FIRST ANSWER IS WRONG (Shan L).
bhcky79 further down is also incorrect. Guys if you're not sure, don't post. Mathematics is easy to mess up, and confusing someone from the start can cause alot of problems to his understanding.

ln is a function, not a number. You can't divide by ln so you can't divide by 10 ln either.

(Shan L, "FUC you third person. I just forgot that 10ln is 10 x ln." ????? LN IS NOT A NUMBER, IT DOESN'T HAVE A VALUE. IT'S A FUNCTION. You can't MULTIPLY BY LN. Run to the nearest place of education, and stop confusing people that are trying to learn.)
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What you have to do step by step is this:
1.You divide both sides by 10, to get rid of the 10 on the right side.
3 = ln (x+3)

2. You need to know what the opposite function of ln is. A simple way of finding and learning it, is by looking at your calculator. On most calculators, you have the "ln" button, and written above it is "e^x". This is the opposite function of ln.
You can try this by calculating ln of 5 (which will give you 1.6094)
now with that answer, you use your second-function key on your calculator to use the "e^x" function. If you did it properly, it will give you 5 again.

Coming back to your question, you know that
3 = ln (x+3)
If you understood the way that e^x is ln's opposite function, you can conclude that
e^3 = (x+3)
since doing e^x on both sides will give you e^3 on the left, and it will cancel the ln on the right, leaving just x+3

3. Now you can simply isolate x, since e^3 is a value (that can be found on your calculator using your e^x key).
You isolate x by substracting 3 on both sides.
e^3 -3 = x

in decimals,
x=17.0855

Answer 2

30 = 10 × ln(x + 3)

You should start by reducing the complexity of the problem.

divide both sides of the equation by 10 to get


3 = 30/10 = ln(x + 3)

or

3 = ln(x + 3)




RULES:

if b = ln(a)

then

exp(b) = a



Therefore if you substitute

b = 3

and

a = (x + 3)


if b = ln(a) = 3

then

a = exp(3) = (x + 3)

therefore:

exp(3) - 3 = x = (20.0855369232 - 3) = 17.0855369232

To check:

Substitute x = 17.0855369232 in the original equation

10 × ln(17.0855369232 + 3) = 10 × ln(20.0855369232)

= (10 × 3) = 30

so the proof checks numerically.






exp( x ) = e ^ x = 2.71828 to the power of x

Answer 3

ln(x) means the natural log of x.
x = e^y is the same as y = ln(x)

So your equation:
30 = 10 ln(x+3) - first divide both sides by 10 to get:

3 = ln(x+3)

then rewrite:

e ^ 3 = x+3

e is a constant with approx value: 2.7182818284
so e^3 = approximately 20.08554
thus x = approximately 17.08554

Answer 4

x=10

Answer 5

30 = 10 * ln (x+3)
3 = ln (x + 3)
e^3 = x + 3
x = e^3 - 3

Answer 6

30 = 10 * ln (x+3)
3 = ln (x + 3)
e^3 = x + 3
x = e^3 - 3
x=17.08555

Answer 7

This is mostly algebra.

30 = 10 ln(x+3)
3 = ln(x+3) [divide by ten]
e^3 = x + 3 [change from logarithmic to exponential form]
x = e^3 - 3 [subtract 3]

Remember, in exponential form:
b^y = x
changed to logarithmic:
log[b] (x) = y

(log[b] means log base b)

Hope this helps.

Answer 8

You don't use any laws but simple algebra. Just trying to isolate x so you divide both sides by 10ln and minus 3 so your answer is (30/10ln)-3 = x. FUC you third person. I just forgot that 10ln is 10 x ln. Yeah i forgot you dumb crap. That's why i said I forgot. I know I cant muliply a function. That's not what I meant. Answer my question now you smart mouth peice of crap.

Answer 9

Stanyan and Cubicmoo are correct, the rest are just joshin you. The key here is to raise both sides as a power of e. When you raise the ln of something to the power of e, it becomes just the something!

Answer 10

x = 3 / ln - 3