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Most Important Selected Qs for JEE AdvancedMathematicsTrigonometry

Which of the following statement(s) is(are) correct?

Options

  1. AIf A=130^ and S= A+ A , then S 0 .
  2. BIf cosec ^2 30^ +k ( 36^ - 18^ )=5 , then k equals 2 .
  3. CThe minimum value of 27 ^2 +3 ^2 is 18 .
  4. DIf a, b are constant real numbers such that a^2 b , then x^2+2 a x+b is always positive x R .

Correct answer

D. If a, b are constant real numbers such that a^2 b , then x^2+2 a x+b is always positive x R .

Step-by-step solution

(A) Clearly, S= 130^ + 130^ = ( 130^ - 40^ )=2 85^ 45^ 0 . (B) Given, cosec ^2 30^ + k ( 36^ - 18^ )=5 aligned & 4+k [ ( 5 +1 4 )- ( 5 -1 4 ) ]=5 & 4+ k 2 =5 k 2 =1 k=2 . aligned (C) Let E =27 ^2 +3 ^2 =(3 3 - 3 )^2+18 . E _ =18. ] (D) Let P(x)=x^2+2 a x+b . If P(x) 0 x R then D 0 4 a^2-4 b 0 a^2 b

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