. Tính bằng cách hợp lí :
2 x 18 x 14 + 3 x 17 x12 + 4 x 69 x 9
2023 x 14 + 2023 x 83 +97
78 x 31 + 78 x 24 + 78 x 17 + 78 x 22 x 72
371 x 69 + 371 x 14 + 629 x 83
91 x 51 + 49 x 163 - 49 x 72
3 x 12 x 17 + 4 x 9 x 81 + 2 x 6 x 6
42 x 17 + 58 x 83 x 42 x 83 + 42 x 83 + 58 x 17
tính bằng cách hợp lý nhất
`@` `\text {Ans}`
`\downarrow`
`2023 \times 14 + 2023 \times 83+97`
`= 2023 \times (14+83) + 97`
`= 2023 \times 97 + 97`
`= 196231 +97`
`= 196328`
`78 \times 31+78 \times 24+78 \times 17+78 \times 22 \times 72`
`= 78 \times (31+24+17+22 \times 72)`
`= 78 \times (31+24+17+1584)`
`= 78 \times 1656`
`= 129168`
`371 \times 69+371 \times 14+629 \times 83`
`= 371 \times (69+14) + 629 \times 83`
`= 371 \times 83 + 629 \times 83`
`= 83 \times (371+629)`
`= 83 \times 1000`
`= 83000`
`91 \times 51+49 \times 163-49 \times 72`
`= 91 \times 51 + 49 \times (163-72)`
`= 91 \times 51+49 \times 91`
`= 91 \times (51+49)`
`= 91 \times 100`
`= 9100`
`3 \times 12 \times 17 + 4 \times 9 \times 81 + 2 \times 6 \times 6`
`= 9 \times 4 \times 17 + 4 \times 9 \times 81 + 4 \times 9 \times 2`
`= 9 \times 4 \times (17+81+2)`
`= 36 \times 100`
`= 3600`
`42 \times 17 + 58 \times 83 \times 42 \times 83 + 42 \times 83 + 17`
`= 17 \times (42+58) + 42 \times 83 \times (58 \times 83 +1)`
`= 17 \times 100 + 3486 \times 4815`
`= 1700 + 16785090`
`= 16786790`
tính nhanh: 2 x 18 x 14 + 3 x 17 x 12 + 4 x 69 x 9
2 x 18 x 14 + 3 x 17 x 12 + 4 x 69 x 9
=(2 x 18) x 14 + (3 x 12) x 17 + (4 x 9) x 69
=36 x 4 + 36 x 17 + 36 x 69
= 36x( 4+17+69)
=36x100
=3600
Chúc bạn học tốt ^_^
2 x 18 x 14 + 3 x 17 x 12 + 4 x 69 x 9
=(2 x 18) x 14 + (3 x 12) x 17 + (4 x 9) x 69
=36 x 4 + 36 x 17 + 36 x 69
= 36x( 4+17+69)
=36x100+
=3600
\(2.18.14+3.17.12+4.69.9\)
\(=\left(2.18\right).14+\left(3.12\right).17+\left(4.9\right).69\)
\(=36.4+36.17+36.69\)
\(=36.\left(4+17+69\right)\)
\(=36.100\)
\(=3600\)
~ Rất vui vì giúp đc bn ~
Tính bằng hai cách
A. 17/19 x12/15 x19/17
B. (5/7+9/7) x 21/28
C. 4/5x13/14+13/14x1/5
Cách hai:
A; \(\dfrac{17}{19}\) x \(\dfrac{12}{15}\) x \(\dfrac{19}{17}\)
= \(\dfrac{68}{95}\) x \(\dfrac{19}{17}\)
= \(\dfrac{4}{5}\)
Cách 1:
A. \(\dfrac{17}{19}\) x \(\dfrac{12}{15}\) x \(\dfrac{19}{17}\)
= (\(\dfrac{17}{19}\) x \(\dfrac{19}{17}\)) x \(\dfrac{12}{15}\)
= \(1\) x \(\dfrac{12}{15}\)
= \(\dfrac{4}{5}\)
B; Cách 1: (\(\dfrac{5}{7}\) + \(\dfrac{9}{7}\)) x \(\dfrac{21}{28}\)
= 2 x \(\dfrac{3}{4}\)
= \(\dfrac{3}{2}\)
Cách 2: (\(\dfrac{5}{7}+\dfrac{9}{7}\)) x \(\dfrac{21}{28}\)
= \(\dfrac{5}{7}\) x \(\dfrac{21}{28}\) + \(\dfrac{9}{7}\) x \(\dfrac{21}{28}\)
= \(\dfrac{15}{28}\) + \(\dfrac{27}{28}\)
= \(\dfrac{42}{28}\)
= \(\dfrac{3}{2}\)
Tính bằng hai cách
A. 17/19 x12/15 x19/17
B. (5/7+9/7) x 21/28
C. 4/5x13/14+13/14x1/5
#Toán lớp 4câu A cách 1
\(\dfrac{17}{19}\times\dfrac{12}{15}\times\dfrac{19}{17}\)
=\(\dfrac{17\times12\times19}{19\times15\times17}\)
=\(\dfrac{12}{15}\)
câu A cách 2
\(\dfrac{17}{19}\times\dfrac{12}{15}\times\dfrac{19}{17}\)
=\(\dfrac{17}{19}\times\dfrac{19}{17}\times\dfrac{12}{15}\)
=1 x \(\dfrac{12}{15}\)
=\(\dfrac{12}{15}\)
Điền kết quả thích hợp vào chỗ chấm: *
Tính bằng cách hợp lí nhất: 198 x 16 + 69 x 198 - 18 x 75 x 11
giupppppppppppppppppp minh can gap
a: Diện tích là:
\(\left(36-4\right):2\cdot\left(36+4\right):2=320\left(m^2\right)\)
b: Khối lượng rau thu được:
\(320\cdot15=4800\left(kg\right)\)
Tính bằng cách hợp lí nhất
A, 18/11 x 22/19 z 38/9
B, 4/7 x 2/5 + 2/5 x 9/7 + 8/7 x 2/5
A ) \(=\dfrac{2\times9\times11\times2\times19\times2}{11\times19\times9}=\dfrac{8}{1}=8\)
b)\(=\dfrac{2}{5}\times\left(\dfrac{4}{7}+\dfrac{9}{7}+\dfrac{8}{7}\right)=\dfrac{2}{5}\times\dfrac{21}{7}=\dfrac{2}{5}\times3=\dfrac{6}{5}\)
Tính bằng cách hợp lí nhất:
a) 19/13 + 14/6 + 1/9 + 4/6 + 7/13 + 17/9
b) 1919/2323 x 464646/747474 x 37/19
Tính bằng cách hợp lý
(40 x 6^16 + 12^9 x 3^7 x 35) : (2^17 x 3^18 x 5)
tính
a) (-11) x (-28) + (-9) x 3
b) (-69) x (-31) - (-15)x12
các bạn ghi cách làm ra cho mik với nha
a) \(\left(-11\right)\cdot\left(-28\right)+\left(-9\right)\cdot3\)
\(=11\cdot28-9\cdot3\)
\(=\left(10+1\right)\cdot28-27\)
\(=28\cdot10+28-27\)
\(=280+1\)
\(=281\)
b) \(\left(-69\right)\cdot\left(-31\right)-\left(-15\right)\cdot12\)
\(=69\cdot31+15\cdot12\)
\(=2139+180\)
\(=2319\)