Question

Tính nhanh

a) 5.(-8).2.(-3)

b)3.(-5)^2+2.(-5)-20

c)34.(15-10)-15.(34-10)

Answer 1

a) 5 x (-8) x 2 x (-3)

= (5 x 2 ) x [(-8)x(-3)]

= 10 x 24

= 240

b) 3 x (-5)² + 2 x ( -5 ) - 20

= 3 x 25 - 2 x 5 - 2 x 10

= 7.5 x 10 - 10 - 2 x 10

= ( 7.5 - 1 - 2 ) x 10

= 4.5 x 10

= 45

c) 34 x ( 15 - 10 ) - 15 ( 34 - 10 )

= [ 34 x 15 - 34 x 10 ] - [ 15 x 34 - 15 x 10 ]

= 34 x 15 - 34 x 10 - 15 x 34 + 15 x 10

= ( 34 x 15 - 15 x 34 ) - ( 34 x 10 - 15 x 10 )

= 0 - 10 ( 34 - 15 )

= 0 - 10 x 19

= -190

Answer 2

Tính nhanh

a) 5.(-8).2.(-3) 

= (5 . 2) . [(-8) . (-3)]

= 10 . 24

= 240

Answer 3

Mình thấy bạn Mai Thanh Xuân đúng rồi

Answer 4

5 . ( -8 ) . 2 . ( - 3 )

= 5 . 2 . ( - 8 ) . ( - 3 )

= 10 . 24

= 240