a) Tính bằng cách thuận tiện nhất:

134 x 4 x 5

= 134 x (4 x 5)

= 134 x 20 = 1680

5 x 36 x 2

= 36x (5 x 2)

= 36 x 10 = 360

42 x 2 x 7 x5

= (42 x 7) x (2 x5)

= 294 x 10 = 2940

b) 137 x 3 + 137 x 97

= 137 x (3 + 97)

= 137 x 100 = 13700

94 x 12 + 94 x 88

= 94 x (12 + 88)

= 94 x 100 = 9400

428 x 12 - 428 x 2

= 428 x (12 - 2) = 4280

537 x 39 - 537 x 19

= 537 x (39 - 19)

= 537 x 20 = 10740

134.4.5= 536.5=2680

b, 42.2.7.5= 84.7.5=588.5=2940

tick nhé

134 x 4 x 5 =134 x ( 4 x 5 ) = 134 x 20 = 2680

42 x 2 x 7 x 5 = (42 x 7) x (2 x 5)= 294 x 10 =2940

giải theo cách từng cặp 1

a) \(134\times4\times5\)

\(=134\times\left(4\times5\right)\)

\(=134\times20\)

\(=2680\)

b) \(5\times36\times2\)

\(=\left(5\times2\right)\times36\)

\(=10\times36\)

\(=360\)

c) \(42\times2\times7\times5\)

\(=42\times7\times\left(2\times5\right)\)

\(=42\times7\times10\)

\(=42\times(7\times10)\)

\(=42\times70\)

\(=2940\)

134 x 4 x 5

= 134 x (4 x 5)

= 134 x 20 = 1680

a.     2 x 134 x 5 = (2 x 5) x 134

                   = 10 x 134

                   = 1340

b. 43 x 95 + 5 x 43

= 43 x (95 + 5)

= 43 x 100 = 4300

2 x 134 x 5 = (2 x 5) x 134

                   = 10 x 134

                   = 1340

2 x 134 x 5 = (2 x 5) x 134

                   = 10 x 134

                   = 1340

Đáp án: 2 x 134 x 5 = (2 x 5) x 134

                           = 10 x 134

                                = 1340