# logarithm

• Jul 16th 2010, 10:54 PM
Zharif93
logarithm
5^(2x) + 5^(3x-1) = 150
• Jul 16th 2010, 11:00 PM
Prove It
Are you sure this isn't supposed to be

$5^{2x} \cdot 5^{3x-1} = 150$?
• Jul 16th 2010, 11:03 PM
Zharif93
im not sure , my friend ask me this question
• Jul 17th 2010, 05:23 AM
HallsofIvy
$5^{2z}= (5^x)^2$ and $5^{3x-1}= \frac{(5^x)^3}{5}$

Your equation is $(5^x)^2+ \frac{(5^x)^3}{5}= 150$. If you let $y= 5^x$ you have $y^2+ y^3/5= 150$ or the cubic polynomial $y^3+ 5y^2= 750$. Any rational solution for y must be a factor of 750. I suggest you whack your friend about the ears!