Other Solution of a Quadratic Equation

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If 5 is one solution of the equation , where m is a constant, what is the other solution?

Review: Other Solution of a Quadratic Equation


Explanation

If 5 is a solution, then we can plug it in and find m:



Therefore, and the equation is:





On the GMAT, when we get a quadratic equation, it can usually be solved by factoring. In this case:



The two question marks must add to +4 and multiply to -45, so we have



The two solutions are and , and we already had 5. The correct answer is (A).


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