1457+49-5+77-797+47=?
Tính nhanh
(-4) . 9 + ( -329 ) - (71 - 136 + 2021)
300 - {5 . [105 - (3^3 . 2 - 49)\(^2\)] + (-10)\(^2\) } : 25
(-36) : 3 + [77 - (-5\(^2\))] . (-12) . 47
a: =-36-329-71+136-2021
=100-400-2021
=-300-2021
=-2321
a.14×99
b.7989×997
c.15373×9998
d.42×53+47×156×47×114
e.5×77×7-7×60+49×25-15×42
a) 1 386
b) 7 965 033
c) 153 699 254
d) 1 846 390 458
e) 2 870
a.14×99
b.7989×997
c.15373×9998
d.42×53+47×156×47×114
e.5×77×7-7×60+49×25-15×42
a) 1 386
b) 7 965 033
c) 153 699 254
d) 1 846 390 458
e) 2 870
\(\left(a\right)14.99=1386\)
\(\left(b\right)7989x997=7965033\)
\(\left(c\right)15373.9998=153699254\)
\(\left(d\right)42.53+47.156.47.114=1846390458\)
\(\left(e\right)5.77.7-7.60+49.25-15.42=2870\)
tính nhanh
53* 39+47*39-53*21-47*21
2*53*12+4*6*87-3*8*40
5*7*77-7*60+49*25-15*42
53x39+47x39-53x21-47x21
=39x ( 53+47) - 21x(53+47)
=39 x100 - 21x100
= 100x(39-21)
=100x18
=1800
2x53x12 +4x6x87 - 3x8x40
= (2x12)x53 + (4x16)x87 - (3x8) x40
= 24x53 + 24x87 + 24x40
= 24( 53+87+40)
= 24x180
=4320
a,53*39+47*39-53*21-47*21
=39*[53+47]-21*[53+47]
=39*100-21*100
=3900-2100
=1800
b,2*53*12+4*6*87-3*8*40
=[2*12]*53+[4*6]*87-[3*8]*40
=24*53+24*87-24*40
=24*[53+87-40]
=24*100
=2400
tính nhanh:
a:53*39+47*39-53*21-47*21
b:2*53*12+4*6*87-3*8*40
c:5*7*77-7*60+49*25-15*42
so sánh qua số trung gian:
a)\(\dfrac{12}{49}\);\(\dfrac{13}{47}\)
b)\(\dfrac{12}{47}\);\(\dfrac{19}{77}\)
giúp mk với
a: \(\dfrac{12}{49}< \dfrac{13}{49}< \dfrac{13}{47}\)
b: \(\dfrac{12}{47}>\dfrac{19}{47}>\dfrac{19}{77}\)
a) Ta chọn phân số \(\dfrac{12}{47}\) là phân số trung gian, ta có :
\(\dfrac{12}{49}< \dfrac{12}{47};\dfrac{13}{47}>\dfrac{12}{47}\Rightarrow\dfrac{12}{49}< \dfrac{13}{47}\)
Tính nhanh :
a)53 . 39 + 47 . 39 - 53 . 21 - 47 . 21
b)2. 53 . 12 + 4 . 6 . 87 - 3 . 8 . 40
c)5 . 7 . 77 - 7 . 60 + 49 . 25 - 15 . 42
Cho dãy số 2; 15; 40; 77;...; 1276; 1457;...
a) Viết tiếp hai số hạng liền sau số 77.
b) Tìm số hạng thứ 20 của dãy số đó.
Tính hợp lý:
a, 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21
b,2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40
c,5 x 7 x 77 - 7 x 60 +49 x 25 -15 x 42.
a, 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21
= 53 x (39-21) + 47 x (93-21)
=53 x 18 + 47 x 18
= (53 +47) x 18
=100 x 18
=1800
b,2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40
=24 x 53 + 24 x 87 - 24 x 40
=24 x (53+87-40)
=24 x 100
=2400
c,5 x 7 x 77 - 7 x 60 +49 x 25 -15 x 42.
=5 x 7 x 77 - 7 x 5 x 12 +49 x 5 x 5 - 5 x 3 x 42.
=5 x 539 - 84 x 5 +245 x 5 -5 x 126
=5 x (539 - 84 +245 -126)
=5 x 574
=2870
a, 53 x 39 + 47 x 39 ‐ 53 x 21 ‐ 47 x 21
= 53 x ﴾39‐21﴿ + 47 x ﴾93‐21﴿
=53 x 18 + 47 x 18
= ﴾53 +47﴿ x 18
=100 x 18
=1800
b,2 x 53 x 12 + 4 x 6 x 87 ‐ 3 x 8 x 40
=24 x 53 + 24 x 87 ‐ 24 x 40
=24 x ﴾53+87‐40﴿
=24 x 100
=2400
c,5 x 7 x 77 ‐ 7 x 60 +49 x 25 ‐15 x 42.
=5 x 7 x 77 ‐ 7 x 5 x 12 +49 x 5 x 5 ‐ 5 x 3 x 42.
=5 x 539 ‐ 84 x 5 +245 x 5 ‐5 x 126
=5 x ﴾539 ‐ 84 +245 ‐126﴿
=5 x 574
=2870
Mi Su
tính nhanh
a. 53 . 39 + 47 . 39 - 53 . 21 - 47 . 21
b. 5 . 7 . 77 - 7 . 60 + 49 . 25 - 15 . 42
c. 100 + 98 + 96 + ... + 2 - 97 - 95 - 93 - ... - 1
d. 1 + 2 - 3 - 4 + 5 + 6 - 7 - 8 + ... + 302
\(53.39+47.39-53.21-47.21\)
\(=39\left(53+47\right)-21\left(53-47\right)\)
\(=39.100-21.6\)
\(=3900-126\)
\(=3774\)
\(b,5.7.77-7.60+49.25-15.42\)
\(=5.7.77-7.5.12+7.7.5.5-3.5.6.7\)
\(=5.7.77-5.7.12+5.7.5.7-5.7.3.6\)
\(=35.77-35.12+35.35-35.18\)
\(=35.\left(77-12+35-18\right)\)
\(=35.82\)
\(=2870\)
\(c,100+98+96+...+2-97-95-93-...-1\)
\(=100+\left(98-97\right)+\left(96-95\right)+...+\left(2-1\right)\)
\(=100+1+1+...+1\)
\(=100+49=149\)