SOLUTION: 90) 3^2x -8 . 3^x +15=0
94) If x= (log125 5)^log5 125
Please help me to solve this two. Thank You
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Question 170139This question is from textbook intermediate algebra
: 90) 3^2x -8 . 3^x +15=0
94) If x= (log125 5)^log5 125
Please help me to solve this two. Thank You
This question is from textbook intermediate algebra
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
90) 3^2x -8(3^x) +15=0
Let w = 3^x
----
Rewrite the quadratic equation:
w^2 - 8w + 15 = 0
(w-5)(w-3) = 0
w = 3 or w = 5
-----------
Solve for x:
3^x = 3 or 3^x = 5
x = 1 or x = [log5/log3] = 1.4649735...
-----------------------------------------
94) If x= (log125 5)^log5 125
log125 5 = log(5)/log(125) = 1/3
log5 125 = 3
-------------------
Therefore x = (1/3)3 = 1
============================
Cheers,
Stan H.
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