giup
Bài 4:
a) 28.76 + 23.28 - 28.13 = 28. (76 + 23 - 13)
= 28. 86
= 2408
b) 80 - (4. 52 - 3 . 23) = 80 - ( 4 . 25 - 3 .8)
= 80 - ( 100 - 24 )
= 80 - 76
= 4
c) 5871 : {928 - [(-82)+247].5} = 5871 : {928 - 165.5}
= 5871 : {928 - 825}
= 5871 : 103
= 57
d) C = 35 + 38 + 41 + .... + 92 + 95 ( có 21 số hạng)
= (95+35) . 21 : 2 = 1365
Bài 5:
a) 22 .5 + (149 - 72) = 4 . 5 + (149 - 49) = 4.5 + 100 = 20 + 100= 120
b) 128. 19 + 128.41 + 128 . 40 = 128 . (19 + 41 + 40) = 128.100 = 12800
c) 136 . 8 - 36 . 23 = 136 . 8 - 36 .8 = 8.(136-36) = 8.100 =800
d) {210 : [16 + 3.(6+3.22)]} - 3 ={210 : [16 + 3.(6+3.4)]} - 3
= {210 : [16 + 3.(6+12)]} - 3
= {210 : [16 + 3.18]} - 3
= {210 : [16 + 54]} - 3
= {210 : 70} - 3
= 3-3 = 0
Bài 4:
a) 28 . 76 + 23 . 28 - 28 . 13 = 2128 + 644 - 364
= 2408
b) 80 - (4 . 52 - 3 . 23) = 80 - (100 - 24)
= 4
giup