InterviewSolution
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InterviewSolution
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If the equation 12x2 – ax + 7 = ax2 + 9x + 3 has only one solution (repeated), then what is the positive internal solution of 'a'?1. 32. 43. 54. 2 |
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Answer» Correct Answer - Option 1 : 3 Given: The equation 12x2 – ax + 7 = ax2 + 9x + 3 Formula used: To have only one solution D = 0 D = b2 – 4ac Calculation: 12x2 – ax + 7 = ax2 + 9x + 3 ⇒ x2(12 – a) – x(9 + a) + 4 = 0 According to the question: ⇒ (9 + a)2 – 4(12 – a)(4) = 0 ⇒ 81 + a2 + 18a – 192 + 16a = 0 ⇒ a2 + 34a – 111 = 0 ⇒ a2 + 37a – 3a – 111 = 0 ⇒ a(a + 37) – 3(a + 37) = 0 ⇒ (a – 3)(a + 37) = 0 If, (a – 3) = 0 ⇒ a = 3 Either, (a + 37) = ⇒ a = – 37 ⇒ a = – 37 is not positive. ∴ The positive internal solution of 'a' is 3. |
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