solve following 4e13 x - 9e5-2 x 0

Question

Solve following 4e^{1+3 x} - 9e^{5-2 x}  = 0 .

Solution

Here the first step is to get one exponential on every side & then we'll divide both sides by one of them (that doesn't matter for the most part) therefore we'll have a quotient of two exponentials. Then the quotient can be simplified & finally we'll get both coefficients on the other side.

Doing all of this gives,

4e^{1+3 x}  = 9e^{5-2 x}

e^{1+3 x} / e^{5-2 x}      = 9/4

e1+3 x-(5-2 x) =  9/4

e^{5 x-4}  =  9/4

Note as well that while we said that it doesn't actually matter which exponential we divide out by doing it the way we did now we'll ignore a negative coefficient on the x.  Not major issue, however those minus signs on coefficients are actually easy to lose on occasion.

Now this is in a form that we can deal with so here's the rest of the solution.

e^{5 x-4}  =  9/4

5x - 4 = ln ( 9/4 )

5x = 4 + ln ( 9/4 )

x =  1/5 (4 ( ln ( 9/4 )) = 0.9621860432

This equation contain single solution of x = 0.9622 .

 Now let's see some equations which involve logarithms. The main property that we'll be using to solve these kinds of equations is,

b^logbx = x