Question

Tính hợp lí :

a. 38 + 41 + 117 + 159 + 62

b. 42 . 53 + 47 . 156 - 47 . 114

Answer 1

a) 38 + 41 + 117 + 159 + 62

= ( 38 + 62 ) + ( 41 + 159 ) + 117

= 100 + 200 + 117

= 300 + 117

= 417

b) 42 . 53 + 47 . 156 - 47 .114

= 42 . 53 + 47 . ( 156 - 114 )

= 42 . 53 + 47 x 42

= 42 . ( 53 + 47 )

= 42 x 100

= 4 200

Answer 2

a,38 + 41 + 117 + 159 + 62

= 38 + 62 + 41 + 159 +117

= ( 38 + 62 ) + ( 41 + 159 ) + 117

= 100 + 200 + 117

= 300 + 117 

= 417

b, 42 x 53 + 47 x 156 - 47 x 114

= 42 x 53 + 47 x ( 156 - 114 )

= 42 x 53 + 47 x 42

= 42 x ( 53 + 47 )

= 42 x 100

= 4200