How do I solve for x in 3^(2x+2)+8*3^(x)-1=0 ?

1 Answer
mizoo
Mar 30, 2018

#x = -2#

Explanation:

#3^(2x+2)+8xx3^(x)-1=0#
#3^(2x) xx 3^2 +8xx3^(x)-1=0#
#(3^ x)^2 xx 9 +8xx3^(x)-1=0#

Let #3^x = a#
#9a^2 + 8a - 1 = 0#
#(a + 1)(9a - 1) = 0#
#a = -1, 1/9#

#3^x = a => #

#3^x = -1:# no solution

#3^x =1/9 #
#3^x = 3^(-2)#
#x = -2#

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