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Grade 12Differential Calculus

If a,b, c, d are positive real numbers such that a + b + c + d = 2, then M = (a + b) (c + d) satisfies the relation :
(A) 0 ≤ M ≤ 1 (B) 1 ≤ M ≤ 2
(C) 2 ≤ M ≤ 3 (D) 3 ≤ M ≤ 4

Profile image of pallavi  pradeep bhardwaj
16 Years agoGrade 12
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1 Answer

Profile image of askiitian.expert- chandra sekhar
16 Years ago

Hi pallavi,

{(a+b)+(c+d)}/2 ≥√{(a+b)(c+d)     since A.M>G.M

2/2 ≥ √M

√M ≤ 1

0≤ M ≤ 1