If 2 and ½ are the zeros of px 2+5x+r, then

(a) p = r = 2   (b) p = r = −2   (c) p = 2, r= −2       (d) p = −2, r = 2

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Question 38 If 2 and ½ are the zeros of px 2+5x+r, then (a) p = r = 2 (b) p = r = −2 (c) p = 2, r= −2 (d) p = −2, r = 2 Let p(x) = px2 + 5x + r Since 2 and ½ are zero of p(x) p(2) = 0 p(2)2 + 5(2) + r = 0 4p + 10 + r 4p + r = −10 p(𝟏/𝟐) = 0 p (𝟏/𝟐)^𝟐+ 5 (𝟏/𝟐) + r = 0 𝒑/𝟒+𝟓/𝟐+𝒓 = 0 Multiplying by 4 both sides p + 10 + 4r = 0 p + 4r = − 10 Since only p = r = −2 satisfies both equations 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 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.