# If #5^(2x) + 3(5)^x = 28#, then what is the value of #x#?

##### 1 Answer

Dec 7, 2016

Let

#t^2 + 3t = 28#

#t^2 + 3t - 28 =0#

#(t + 7)(t - 4) = 0#

#t= -7 and 4#

Now, since

#5^x = -7 and 5^x = 4#

#ln(5^x) = ln(-7) and ln(5^x) = ln4#

#x = O/ and xln5 = ln4#

#x = ln4/ln5#

Hopefully this helps!