in a quiz competition, a student answers n questions correctly and was given D(n + 50) for each question correctly answered. If he gets D600.00 altogether, how many questions did he answer correctly?
A. 18 B. 15 C. 12 D. 10
Correct Answer: D
Explanation
let the number of question = n n(n + 50) = 600 n2 + 50n - 600 - 0 by quadratic formular x = \(\frac{b \pm \sqrt{b^2 - 4ac}}{2}\) n = \(\frac{-50 \pm \sqrt{50^2 - 4(1) (-600)}}{2(1)}\) = \(\frac{-50 \pm \sqrt{4900}}{2}\) = \(\frac{-50 + 70}{2}\) = \(\frac{20}{2}\) = 10
