Question 750798
{{{4^(2x)+1 = 671}}}

Subtract 1 from both sides:

{{{4^(2x)=670}}}

Take log base 4 of both sides.  All you are left with on the left side is 2x. So 2x= log base 4 of 670.  Using a change of base formula, 2x= (log 670) / (log 4).  Divide both sides by 2, x is about 2.347.