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Mathematics 17 Online
OpenStudy (anonymous):

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OpenStudy (dumbcow):

a) looks like a simple linear equation, is that correct?

OpenStudy (anonymous):

Correction on a. Its actually 3^(2x) = 5(3^x) + 36. i forgot to add the ^ symbols

OpenStudy (dumbcow):

ahh thought so

OpenStudy (anonymous):

Sorry about that:)

OpenStudy (anonymous):

for the first, try rewriting in quadratic form: (3^x)^2 -5(3^x) -36 = 0

OpenStudy (dumbcow):

ok you can either make everything have same base, then set exponents equal or like in part a) make substitution u = 3^x, it becomes a quadratic

OpenStudy (anonymous):

u^2 - 5u -36 = 0 (u-9)(u+4) = 0 u=9, -4 so now solve: 3^x = 9 and 3^x = -4 but you already know this second one does not have a solution.

OpenStudy (anonymous):

All of these are exponential equations. You'll need to use logarithms to solve. Hopefully that will help.

OpenStudy (callisto):

For (a) 3^(2x) = 5(3^x) + 36 (3^x)^(2) = 5(3^x) + 36 (3^x)^(2) - 5(3^x) - 36 =0 [(3^x) -9][(3^x)+4] =0 [(3^x) -9]=0 or [(3^x)+4] =0 (3^x) = 9 or (3^x)=-4 xlog3 = log9 or xlog3 = log(-4) (rejected) x=2

OpenStudy (callisto):

@dpalnc 3^(2x) =/= (3^x)^2

OpenStudy (anonymous):

\[1/8^{x-3}=2\times16^{2x-1}\] => \[2^{-3(x-3)} = 2\times2^{4(2x+1)}\] => \[2^{-3x+9}=2^{(8x+4)+1}\] => Since both sides are equal then we can say that their exponents are equal, thus we get: \[-3x+9 = 8x+5\] Solve for X.

OpenStudy (anonymous):

I only did the one problem. You can use the same technique to solve for the others.

OpenStudy (anonymous):

Also, as with pretty much every math problem, make sure you check your answers. :)

OpenStudy (callisto):

technique needed for (c) is similar to that in (b) so the answer from Quaternions can serve as a reference for you

OpenStudy (anonymous):

Thank you so much for helping me guys! @clallisto, i particularly found your information very helpful! Il try to do my best with this questions. I really appreciate the time and help for everyone who answered! Have a blessed day! :)

OpenStudy (callisto):

welcome. God blessed! try (c) now ~

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