# Math question... I need help!

It’s a logarithm question, it says: “Solve the equation 5 power 2x + 7(5 power x) -30 =0

Can you please give me an explanation to the answer?

PS: it’s not a HW question and I already know the answer, it’s just that I need someone to explain the steps

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## 6 Answers

Post the answer to show that you know it.

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[mod says] Please do not provide the actual answer to the problem. Only help in solving it. Thanks!

@augustlan okay. I thought I can, since it’s not a home work.

Here, again, just the first trick and links to follow.

Your equation:

5^2x + 7*(5^x) – 30 = 0

Rearranging.

[(5^x)^2] + 7*(5^x) – 30 = 0

Now, the trick is, put y = 5^x,

y^2 + 7*y – 30 = 0

From this on, solve the quadratic equation, get two values of y. Test the values. Apply logarithms, and solve to get the answer.

For logarithms, you may refer:

Basics of logarithms

Log rules

Simplifying logarithms (6th bullet point)

Changing base of log

So, with start as above, and all the links, you should get your answer.

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