Câu hỏi của Thuyết Dương

Question

Câu 1.  Tính: a.  A = 4 + 2 2 + 2 3 + 2 4 +. . . + 2 20 b.  tìm x biết:  ( x + 1) + ( x + 2) + . . . + ( x + 100) = 5750.

Thuyết Dương · Accepted Answer

Câu 1.   a).  2A = 8 + 2 3 + 2 4 + . . . + 2 21. => 2A – A = 2 21 +8 – ( 4 + 2 2 ) + (2 3 – 2 3) +. . . + (2 20 – 2 20).  = 2 21.      b).          (x + 1) + ( x + 2 ) + . . .  . . . . . + (x + 100)  = 5750=>             x + 1 + x + 2 + x + 3 + . . . . . . .. . .. . . . + x + 100     =  5750=>   ( 1 + 2 + 3 + . .  . + 100) + ( x + x + x . . . . . . . + x )   =  5750=>             101 . 50              +                100 x                          = 5750                                                         100 x + 5050      =  5750                                                         100 x     = 5750 – 5050                                                          100 x     =  700                                                                x     =  7                                          101 . 50              +                100 x                          = 5750                                                         100 x + 5050      =  5750                                                         100 x     = 5750 – 5050                                                          100 x     =  700                                                                x     =  7Câu trả lời: Câu 1.   a).  2A = 8 + 2 3 + 2 4 + . . . + 2 21. => 2A – A = 2 21 +8 – ( 4 + 2 2 ) + (2 3 – 2 3) +. . . + (2 20 – 2 20).  = 2 21.      b).          (x + 1) + ( x + 2 ) + . . .  . . . . . + (x + 100)  = 5750=>             x + 1 + x + 2 + x + 3 + . . . . . . .. . .. . . . + x + 100     =  5750=>   ( 1 + 2 + 3 + . .  . + 100) + ( x + x + x . . . . . . . + x )   =  5750=>             101 . 50              +                100 x                          = 5750                                                         100 x + 5050      =  5750                                                         100 x     = 5750 – 5050                                                          100 x     =  700                                                                x     =  7                                          101 . 50              +                100 x                          = 5750                                                         100 x + 5050      =  5750                                                         100 x     = 5750 – 5050                                                          100 x     =  700                                                                x     =  7

Thuyết Dương · Answer

Câu 1.   a).  2A = 8 + 2 3 + 2 4 + . . . + 2 21. => 2A – A = 2 21 +8 – ( 4 + 2 2 ) + (2 3 – 2 3) +. . . + (2 20 – 2 20).  = 2 21.       b).          (x + 1) + ( x + 2 ) + . . .  . . . . . + (x + 100)  = 5750=>             x + 1 + x + 2 + x + 3 + . . . . . . .. . .. . . . + x + 100     =  5750=>   ( 1 + 2 + 3 + . .  . + 100) + ( x + x + x . . . . . . . + x )   =  5750=>                101 . 50              +                  100 x                 = 5750                                                         100 x + 5050      =  5750                                                         100 x     = 5750 – 5050                                                          100 x     =  700                                                                x     =  7Câu trả lời: Câu 1.   a).  2A = 8 + 2 3 + 2 4 + . . . + 2 21. => 2A – A = 2 21 +8 – ( 4 + 2 2 ) + (2 3 – 2 3) +. . . + (2 20 – 2 20).  = 2 21.       b).          (x + 1) + ( x + 2 ) + . . .  . . . . . + (x + 100)  = 5750=>             x + 1 + x + 2 + x + 3 + . . . . . . .. . .. . . . + x + 100     =  5750=>   ( 1 + 2 + 3 + . .  . + 100) + ( x + x + x . . . . . . . + x )   =  5750=>                101 . 50              +                  100 x                 = 5750                                                         100 x + 5050      =  5750                                                         100 x     = 5750 – 5050                                                          100 x     =  700                                                                x     =  7

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