Jamia Millia Islamia MCA 2017
If the roots of the equation are equal, then , , are in
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Answer: Option C โ A.P.
Detailed Solution
The coefficients add to , so is a root.
Equal roots means both roots are 1, so the product .
, i.e. : , , are in A.P.
โ Check
gives , which has equal roots.โ Common trap
(B) G.P. fails: with 1, 2, 4 the equation is , whose roots 1 and are not equal.Quick tip
Coefficient sum root 1; equal roots
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Quadratic Equations โ Preparation
This question tests your understanding of Quadratic Equations, a key topic in the Quantitative Aptitude section. The detailed solution above uses a step-by-step approach to show the reasoning, and where available, a shortcut that helps you solve similar questions in under 90 seconds during the actual exam.
A quadratic equation has the form ax^2 + bx + c = 0, where a is not zero. This topic covers solving quadratics by factorisation and by the quadratic formula, the nature of roots using the discriminant b^2 - 4ac, the sum (-b/a) and product (c/a) of roots, and forming an equation from its roots. In aptitude exams, a common question type gives two quadratic equations and asks you to compare their roots (whether x > y, x < y and so on). In engineering and MCA entrance exams, questions also test conditions on roots, common roots, and symmetric expressions such as the sum of squares of roots. Using the sum and product of roots is usually far faster than finding the roots themselves. Practise the quadratic equation questions below, each with a step-by-step solution.