What is the solution to the equation 9^(x - 2) = 27
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OpenStudy (lgbasallote):
hint:
9 = 3^2
27 = 3^3
does that help?
OpenStudy (anonymous):
um kinda
OpenStudy (anonymous):
x = 2.5
x = 3.5
x = 0.5
x = -0.5
are my answer choices
OpenStudy (anonymous):
Can someone help me?
OpenStudy (lgbasallote):
so apply my hint to the problem..
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OpenStudy (anonymous):
I don't understand? I thought it would be 5 but thats not a answer choice
OpenStudy (anonymous):
or 27 = 9^(3/2)
OpenStudy (anonymous):
9^3 = 729
OpenStudy (lgbasallote):
okay so you have
\[\Large 9^ {x-2} = 27\]
apply my hint here (3^2 = 9; 3^3 = 27)
\[\Large \implies (3^2)^{x-2} = 3^3\]
does that help?
OpenStudy (anonymous):
so 3x^-4 = 9?
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OpenStudy (anonymous):
i mean 3x^4 = 28
OpenStudy (lgbasallote):
how did you get that?
OpenStudy (anonymous):
3 times x = 3x and 2 times -2 is negative 4 and 3^3 is 27
OpenStudy (lgbasallote):
why did you multiply 3 by x?
OpenStudy (anonymous):
bevause x is on the outside of the parenthesis
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OpenStudy (lgbasallote):
hmm well you did something close to what was supposed to happen
you apply the rule
\[\large (a^m)^n = a^{mn}\]
so that means \[\Large (3^2)^{x-2} = 3^3\]
becomes\[\Large \implies 3^{2x - 4} = 3^3\]
got it?
OpenStudy (anonymous):
kinda
OpenStudy (lgbasallote):
so now use the rule \[\Large a^x = a^y \Longleftrightarrow x = y\]
OpenStudy (anonymous):
so the answer is 3.5
OpenStudy (lgbasallote):
sounds right
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