Wednesday, 11 February 2015

SOLUTION IN 41 TO 50

  
41.   Given exp. =[(a + b)² - 4ab], where a =476 and b =424
                     = [(476 + 424)² - 4 x 476 x 424]
                     = [(900)² - 8072296 = 810000 – 807296 =2704

42.   (112 x 5⁴) = 112 x (10/2)² = 112 x 10⁴/2⁴ = 1120000/16 = 70000.

43.   935421 x 625 = 935421 x 5² = 935421 x (10/2)²

                   935421 x 10⁴   =   9354210000
                             2⁴                         16
                         = 584638125.
44.   12345679 x 72=  12345679 x (70 + 2)
                    = 12345679 x 70 + 123455679 x 2
                       = 864197530 + 24691358                                     864197530
                      =888888888                                                              24691358
                                                                                                          888888888

45.   Given exp. = (397)² + (104)² + 2 x 397 x 104
                   = (397 + 104)² = (501)² = (500 + 1)²
                   = (500)² +  1² + 2 x 500 x 1 = 250000 +1 + 1000
                   = 251001
46.   20 x X = (64 +36) (64 – 36) = 100 x 28

                                    X = 100 x 28               = 140.
                                                                 20

47.Given exp. = ( a + b)² - (a – b)² = 4ab             =4
                               ab                        ab

48.Given exp. (a + b) ² + ( a –b )²   =  2 (a² + b²)                 =2
                       (a² + b²)                            (a² + b²

49.Given exp. (a³ + b³)              (a + b) = (768 +232) = 1000.
                                  (a² -ab + b²)

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