tính hợp lí
a) 28x(231+69)+72x(231+69)
b) 10x46x95+69x120/84:312-611
c)1+2+22+2324+.....+2100
d)5+53+55+.....+597+599
Tinh nhanh:
28x(231+69)+72x(231+69)
28 x (231+69)+72 x (231+69)
=28 x 300+72 x 300
=(28+72) x 300
=100 x 300
=30000
\(=28x300+72x300=300x\left(28+72\right)=300x100=30000\)
28 x (231 + 69) + 72 x (231 + 69)
= (231 + 69) x ( 28 + 72)
= 300 x 100
= 30000
(Nhớ k cho mình với nhoa!)
Tính hợp lí
a) A = 1 + 2 + 2 2 + 2 3 + 2 4 + . . . + 2 99 + 2 100 .
b) B = 5 + 5 3 + 5 5 + . . . + 5 97 + 5 99 .
Tính hợp lí:
a, A = 1 + 2 + 2 2 + 2 3 + 2 4 + . . . + 2 99 + 2 100
b, B = 5 + 5 3 + 5 5 + . . . + 5 97 + 5 99
a, Ta có :
A = 1 + 2 + 2 2 + 2 3 + 2 4 + . . . + 2 99 + 2 100
2A = 2 + 2 2 + 2 3 + 2 4 + . . . + 2 99 + 2 100 + 2 101
A = 2A – A = ( 2 + 2 2 + 2 3 + 2 4 + . . . + 2 99 + 2 100 + 2 101 ) –( 1 + 2 + 2 2 + 2 3 + 2 4 + . . . + 2 99 + 2 100 )
= 2 + 2 2 + 2 3 + 2 4 + . . . + 2 99 + 2 100 + 2 101 – 1 - 2 - 2 2 - 2 3 - 2 4 - . . . - 2 99 - 2 100
= 2 101 - 1
Vậy A = 2 101 - 1
b, Ta có.
B = 5 + 5 3 + 5 5 + . . . + 5 97 + 5 99
5 2 B = 5 2 ( 5 + 5 3 + 5 5 + . . . + 5 97 + 5 99 )
25B = 5 3 + 5 5 + . . . + 5 97 + 5 99 + 5 101
25B – B = ( 5 3 + 5 5 + . . . + 5 97 + 5 99 + 5 101 ) – ( 5 + 5 3 + 5 5 + . . . + 5 97 + 5 99 )
24B = 5 3 + 5 5 + . . . + 5 97 + 5 99 + 5 101 – 5 - 5 3 - 5 5 - . . . - 5 97 - 5 99
24B = 5 101 - 5
B = 5 101 - 5 24 = 5 5 100 - 1 24
Vậy B = 5 5 100 - 1 24
tính hợp lí
a.12.25+29.25+59.25=
b.28.(231+69)+72.(231+69)=
c.49.27+51.27+27=
d.53.11
79.101
a)25.(12+29+59)=25.100=2500
b)(231+69)(28+72)=300.100=30000
c)27(49+51)+27=27.100+27=2700+27=2727
d)là sao ko hiểu nếu là phân số bằng
583/7979
a. = 25.(12+29+59) = 25.100 = 2500
b. = 28.300 + 72.300 = 300.100 = 30000
c. = 27.(49+51+1) = 27.101 = 2727
d. 53.11 = 583
79.101 = 7979
a,12*25+29*25+59*25
=25(12+29+59)
=25*100
=2500
b,28(231+69)+72(231+69)
=(231+69)(28+72)
=300*100
=30000
c,49*27+51*27+27
=27(49+51)+27
=27*100+27
=2700+27
=2727
d,53*11
=53*10+53*1
=530+53
=583
79*101
=79*100+79*1
=7900+79
=7979
D=5+53+55+..........+597+599=???
Ta có D = 5 + 53 + 55 + ... + 597 + 599
52D = 53 + 55 + 57 + ... + 599 + 5101
52D - D = ( 53 + 55 + 57 + ... + 599 + 5101 ) - ( 5 + 53 + 55 + ... + 597 + 599 )
24D = 5101 - 5
D = \(\dfrac{5^{101}-5}{24}\)
thuc hien phep tinh
a, 28(231+69) + 72(231+69)
b, 2017 - { 52 . 22 - 11 .[72 - 5.23 + 8 . ( 112 - 121 )
c, 1+ 8 + 15 + 22 + 29 + ...... + 407 + 414
GIUP MIK VS NHE
AI NHANH MIK CHO K
giúp mik với, tick 3 bạn đầu
Tính nhanh
28.(231+69) +72(231+69)
Tính nhanh
28.(231+69) +72(231+69)
= 28 x 300 + 72 x 300
= (28+72) x 300
= 100 x 300
= 30000
#Học tốt!
Chúc bn ngày mới vui vẻ!
28 . ( 231 + 69 ) + 72 . ( 231 + 69 )
tính nhanh
28 . ( 231 + 69 ) + 72 . ( 231 + 69 )
= ( 231 + 69 ) . ( 72 + 28 )
= 300 . 100
= 30000
=28.231+28.69+72.231+72.69
=28.231+72.231+28.69+72.69
=231.(72+28)+69.(28+72)
=231.100+69.100
=32100+6900
=39000
Tính
1) 12.2.25+29.25+59.25
2) 25.(231+69)+72.(231+69)
3) 39.(250+87)+64.(240+97)
4) 36.28+36.82+64.69+64.41
1) 12.2.25+29.25+59.25
=24.25+29.25+59.25
=25(24+29+59)
=25.112
=2800
2) 25.(231+69)+72.(231+69)
=25.300+72.300
=300(25+72)
=300.97
=29100
3) 39.(250+87)+64.(240+97)
=39.337+64.337
=337.(39+64)
=337.103
=34711
4) 36.28+36.82+64.69+64.41
=36.(28+82)+64.(69+41)
=36.110+64.110
=110(36+64)
=110.100
=11000
Đăng từng bài thôi nha bạn.
12 x 2 x 25 + 29 x 25 + 59 x 25 = 2800
25 x ( 231 + 69 ) + 72 x ( 231 + 69 ) = 29100
39 x ( 250 + 87 ) + 64 x ( 240 + 97 ) = 34711
36 x 28 + 36 x 82 + 64 x 69 + 64 x 41 = 11000
Cho mik xin đúng nhá