RS Aggarwal - Mathematics

Book: RS Aggarwal - Mathematics

Chapter: 10. Quadratic Equations

Subject: Maths - Class 10th

Q. No. 36 of Exercise 10C

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36

Find the roots of each of the following equations, if they exist, by applying the quadratic formula:

12abx2 – (9a2 – 8b2)x – 6ab = 0, where a ≠ 0 and b ≠ 0

Given: 12abx2 – (9a2 – 8b2)x – 6ab = 0

Comparing with standard quadratic equation Ax2 + Bx + C = 0


A = 12ab, B = – (9a2 – 8b2), C = – 6ab


Discriminant D = B2 – 4AC


= [ – (9a2 – 8b2)]2 – 4.12ab. – 6ab


= 81a4 – 144a2b2 + 64b4 + 288 a2b2


= 81a4 + 144a2b2 + 64b4


= (9a2 + 8b2)2 > 0 Using a2 + 2ab + b2 = (a + b)2


Hence the roots of equation are real.



= 9a2 + 8b2


Roots are given by





Hence the roots of equation are


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