If the distance between the points (2, –2) and (–1, x) is 5, one of the values of x is

(A) –2  

(B) 2  

(C) –1  

(D) 1

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Question 1 If the distance between the points (2, –2) and (–1, x) is 5, one of the values of x is (A) –2 (B) 2 (C) –1 (D) 1 Given Distance between (2, −2) and (−1, x) = 5 √(( −1 −2)2+(𝑥−(−2))2) = 5 √(( −3)2+(𝑥+2)2) = 5 √(9+𝑥^2+2^2+4𝑥) = 5 √(9+𝑥^2+4+4𝑥) = 5 √(𝑥^2+4𝑥+13) = 5 Squaring both sides (√(𝑥^2+4𝑥+13))^2 = 52 x2 + 4x + 13 = 25 x2 + 4x + 13 − 25 = 0 x2 + 4x − 12 = 0 Solving by splitting the middle term x2 + 6x − 2x − 12 = 0 x(x + 6) − 2(x + 6) = 0 (x − 2) (x + 6) = 0 ∴ x = 2, −6 So, the correct answer is (B)

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science and Computer Science at Teachoo