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Example 9 - Chapter 4 Class 10 Quadratic Equations (Term 2)

Last updated at Aug. 3, 2021 by

Example 9 - Find roots of 4x2 + 3x + 5 = 0 by completing sq - Solving by completing square

Example 9 - Chapter 4 Class 10 Quadratic Equations - Part 2
Example 9 - Chapter 4 Class 10 Quadratic Equations - Part 3

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Example 9 Find the roots of 4x2 + 3x + 5 = 0 by the method of completing the square. 4x2 + 3x + 5 = 0 Dividing by 4 4𝑥2/4+3𝑥/4+5/4=0 x2 + 3𝑥/4+5/4=0 We know that (a + b)2 = a2 + 2ab + b2 Here, a = x & 2ab = 3𝑥/4 2xb = 3𝑥/4 2b = 3/4 b = 3/4×1/2 b = 3/8 Now, in our equation x2 + 3𝑥/4+5/4=0 Adding and subtracting (3/8)^2 x2 + 3𝑥/4+5/4+(3/8)^2−(3/8)^2=0 x2 + 3𝑥/4+(3/8)^2+5/4−(3/8)^2=0 (𝑥+3/8)^2+5/4−(3/8)^2=0 (𝑥+3/8)^2=(3/8)^2−5/4 (𝑥+3/8)^2=9/64−5/4 (𝑥+3/8)^2=(9 − 5(16))/64 (𝑥+3/8)^2=(9 − 80)/64 (𝑥+3/8)^2=(−71)/64 Since square of any number cannot be negative So, answer does not exist

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.