solving equations involving logarithm??

[wendywoo]

2^x+1 =36

the answer is log36/log2-1=4.17 but i have no idea why log was involved and how to solve it.

 

[burakaltr]

2^x+1 =36

the answer is log36/log2-1=4.17 but i have no idea why log was involved and how to solve it.

If 2**(x+1) = (2)**2 times 3**2

2**(x-1)=3**2=9
take ln of both sides

(x-1) ln2 = 2 ln3

x= ( 2 ln3 / ln2 ) + 1


You can use logarithmic tables and find ln 3 and ln 2 readily