Page 6 - Real Number System_Neat
P. 6

∴ The required solution is    ∈ (−∞, 0) ∪ (2, ∞)




                                 2
               f) 6 + 5   −    ≥ 0

                 Solution:

                 Here,


                                  2
                 6 + 5   −    ≥ 0
                 The corresponding equation of given inequality is


                                  2
                 6 + 5   −    = 0
                                            2
                 or, 6 + 6   −    −    = 0

                 or, 6(1 +   ) −   (1 +   ) = 0

                 or, (1 +   )(6 −   ) = 0


                 ∴    = −1, 6                                       − ∞          -1           6        ∞

                 These two points divide the real line into 3 sub-intervals as shown

                   in figure.

                 Now,




                                                                 Sign of
                                 Interval
                                                1 +         6 −     (1 +   )(6 −   )
                                 (-∞, -1)          −          +                 −
                                  (-1, 6)          +          +                 +


                                  (6, ∞)           +          −                 −

                                                                  2
                 Also, for    = −1       6, 6 + 5   −    = 0.

                 ∴ The required solution is    ∈ [−1, 6]
   1   2   3   4   5   6   7   8