SOLUTION: 1. Find "x" for these 2 problems a)9^2x=2*(9^x)+3 b)3*(3^x)+9*(3^-x)=28 ive graduated 2years ago and i dont remember how to do those 2 problems id like to know how to solve t

Algebra ->  Algebra  -> Logarithm Solvers, Trainers and Word Problems -> SOLUTION: 1. Find "x" for these 2 problems a)9^2x=2*(9^x)+3 b)3*(3^x)+9*(3^-x)=28 ive graduated 2years ago and i dont remember how to do those 2 problems id like to know how to solve t      Log On

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Question 108230: 1. Find "x" for these 2 problems
a)9^2x=2*(9^x)+3
b)3*(3^x)+9*(3^-x)=28
ive graduated 2years ago and i dont remember how to do those 2 problems
id like to know how to solve them step by step thanks
yours
brian
Answer by scott8148(5880) About Me  (Show Source):
You can put this solution on YOUR website!
a) let z=9^x ... z^2=2z+3 ... z^2-2z-3=0 ... (z-3)(z+1)=0 ... z=3, z=-1
... the negative value is not realistic ... 3=9^x ... x=1/2

b) multiplying by 3^x gives 3*(3^x)^2+9=28(3^x) ... the method of solution is similar to a)