Ex 4.3, 1 (ii) - Ex 4.3

Ex 4.3, 1 (ii) - Chapter 4 Class 10 Quadratic Equations - Part 2

Ex 4.3, 1 (ii) - Chapter 4 Class 10 Quadratic Equations - Part 3

Ex 4.3, 1 (ii) - Chapter 4 Class 10 Quadratic Equations - Part 4

  1. Chapter 4 Class 10 Quadratic Equations (Term 2)
  2. Serial order wise

Transcript

Ex 4.3 ,1 Find the roots of the following quadratic equations, if they exist, by the method of completing the square: (ii) 2x2 + x โ€“ 4 = 0 2x2 + x โ€“ 4 = 0 Dividing whole equation by 2 (2๐‘ฅ2 + ๐‘ฅ โˆ’ 4)/2=0/2 2๐‘ฅ2/2+๐‘ฅ/2โˆ’4/2=0 x2 + ๐‘ฅ/2โˆ’2=0 We know that (a + b)2 = a2 + 2ab + b2 Here, a = x & 2ab = ๐‘ฅ/2 2xb = ๐‘ฅ/2 2b = 1/2 b = 1/2 ร— 1/2 b = 1/4 Now, in our equation x2 + ๐‘ฅ/2โˆ’2=0 Adding and subtracting (1/4)^2 x2 + ๐‘ฅ/2โˆ’2+(1/4)^2โˆ’(1/4)^2= 0 x2 + ๐‘ฅ/2+(1/4)^2โ€“ 2 โ€“ (1/4)^2=0 (๐‘ฅ+1/4)^2โˆ’2โˆ’(1/4)^2= 0 (๐‘ฅ+1/4)^2โˆ’2 โˆ’1/16=0 (๐‘ฅ+1/4)^2=2+1/16 (๐‘ฅ+1/4)^2=(2(16) + 1)/16 (๐‘ฅ+1/4)^2=(32 + 1)/16 (๐‘ฅ+1/4)^2=33/16 (๐‘ฅ+1/4)^2=(โˆš33/4)^2 Cancelling square both sides ๐‘ฅ+1/4 = ยฑ โˆš33/4 Solving So, the root of the equation are x = (โˆš33 โˆ’ 1)/4 & x = (โˆ’(โˆš33 + 1))/4

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 10 years. He provides courses for Maths and Science at Teachoo.