bài 1: tìm số chưa biết x thuộc N
1/60-3.(x-2)=51
2/ 3.(x-36): 18 = 12
3/ (x-3)3 = 27
4/ 2x- 15 = 17
5/ ( 3x - 24) .73=2.74
6/ [( 6x - 39) : 3].28=5628
7/( 3x - 15)2 - 6 = 75
8/ 128 - 3 . (x +4)=23
9/ (12x -43 ).83=4.84
10/ 720: [41- (2x - 5)]= 23 . 5
1/ 3(x - 2) = 9 => x - 2 = 3 => x = 5
2/ 3(x - 36) = 216 => x - 36 = 72 => x = 108
3/ (x - 3)3 = 33 => x - 3 = 3 => x = 6
4/ 2x = 32 => 2x = 25 => x = 5
5/ 3x - 16 = 2.74 : 73 = 14 => 3x = 30 => x = 10
6/ (6x - 39) : 3 = 201 => 6x - 39 = 603 => 6x = 642 => x = 107
7/ (3x - 15)2 = 81 => (3x - 15)2 = 92 => 3x - 15 = 9 => 3x = 24 => x = 8
8/ 3(x + 4) = 105 => x + 4 = 35 => x = 31
9/ 12x - 43 = 4.84 : 83 = 32 => 12x = 32 : 64 => 12x = 1/2 => x = 1/24
10/ 41 - (2x - 5) = 680 => 2x - 5 = -639 => 2x = -634 => x = - 317