SAT Math: Algebra


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Read the question carefully.  This question requires you to know exponent rules.  It is important for you to note that a and b are positive integers and that you are asked for a in terms of b.

Identify the bottom line.  a = ?

Assess your options.  Unfortunately, this problem is going to be difficult for you to solve if you have not memorized exponent rules.  If the rules you need to solve this problem do not immediately pop into your head, go back and review the exponent rules.  

Attack the problem.  There are two rules that apply to this problem:

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The first thing you have to do is get all the bases to look the same.  Look back at the original equation:

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The number 9 is three squared, so you can rewrite the equation like this:

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Now apply the first exponent rule to the left side of the equation:

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Now you can apply the second rule.  If the base is 3 on both sides, then the exponents must be the same number.  Set them equal to one another and solve for the variable.

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Loop back.  You found a in terms of b, so now you just need to select the correct answer choice, which is (B).

Correct answer: (B)

This is a medium level question.


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