Question

1. tính (tính nhanh nếu đc)

a) 49-37 +10

b)57.49 +57. 51 -120

c)1250-11.[ 37 (2 . 3² -15)²

2. tìm x

a) 2.x + 17 = 3³

b) 4 . ( x -23 ) = 120

 

Answer 1

a. 49 - 37 + 10 = 12 + 10 = 22

b. 57 . 49 + 57 . 51 - 120 = 57 . ( 49 + 51 ) -120 = 57 . 100 -120 = 5700 - 120 = 5580

c. 1250 - 11 . [ 37 . (2.3² -15)² ] =1250 - 11 .[ 37.  3² ] = 1250 - 11 . 333 = 1250 - 3663 = -2413

2x + 17 = 3 ³

2x + 17 = 27

2x         = 27 - 17

2x         =   10

x           =  10 : 2

x           =     5

4 . (x - 23 ) = 12

       x - 23  =  12 : 4

       x - 23  =      3

      x           =   23 - 3

      x          =    20

Answer 2

a)49-37+10

=49-(37+10)

=49-47

=2

b)57.49 +57. 51 -120

=57.(120+57).(51-49)

=57.(177.2)

=57.354

=20178

c)1250-11.[ 37 (2 . 3² -15)²

=1250-11.[37.(2.9-15)²

=1250-11.(37.3²)

=1250-11.(37.9)

=1509.333

=502497.