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Solve for x:log2(x^2-3x)=log2(5x-15).(a) 2, 5(b) 7(c) 23(d) 3, 5I had been asked this question in an interview.I'm obligated to ask this question of Discrete Probability topic in chapter Discrete Probability of Discrete Mathematics

Answer»

The CORRECT answer is (d) 3, 5

To ELABORATE: By using the property if logax = logay then x=y, GIVES 2x^2-3x=10-6x. Now, to solve the equation x^2-3x-5x+15=0 ⇒ x^2-8x+15 ⇒ x=3, x=5

For x=3:log2(3^2-3*3) = log2(5*3-15) ⇒ true

For x=5:log2(5^2-3*5) = log2(5*5-15) ⇒ true

The solutions to the equation are : x=3 and x=5.



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