Tính hợp lý: 25.13.4 + 2.17.50
2.24.2 + 3.41.16 + 6.2.8.17
Tính nhanh:
2.24.25 + 3.41.16 + 6.2.8.17
=48*25+48*41+48*34
=48*(25+41+34)
=48*100=4800
`@` `\text {Ans}`
`\downarrow`
`2.24.25 + 3.41.16 + 6.2.8.17`
`= 48*25 + 48*41 + 48*2*17`
`= 48*(25+41+2*17)`
`= 48*(66+34)`
`= 48*100 `
`= 4800`
Tính nhanh:
2.24.25+3.41.16+6.2.8.17
2.24.25 + 3.41.16 + 6.2.8.17
= ( 2.24 ).25 + ( 3.16 ).41 + ( 6.8 ) + ( 2.17 )
= 48 . 25 + 48 .41 + 48 . 34
= 48. ( 25 + 41 + 34 )
= 48 . 100
= 4800
\(2.24.25+3.41.16+6.2.8.17\\ =\left(2.24\right).25+\left(3.16\right).41+\left(6.8\right)\left(2.17\right)\\ =48.25+48.41+48.34\\ =48.\left(25+41+34\right)\\ =48.100\\ =4800\)
tính nhanh:
3.18.25+3.41.16+6.2.8.17
3.18.25 + 3.41.16 + 6.2.8.17
= 3.18.25 + 3.16.41 + (6.8).(2.17)
= 48.25 + 48.41 + 48.34
= 48.(25 + 41 + 34)
= 48.100
= 4800
2.24.25+3.41.16+6.2.8.17
nhanh nha
^^Thảo^^
tính nhanh :
2.24.25 + 3.31.16 + 6.2.8.17
\(2.24.25+3.31.16+6.2.8.17\)
\(=48.25+48.31+48.34\)
\(=48.\left(25+31+24\right)\)
\(=48.90\)
\(=4320\)
=48*25+48*31+48*34
=48(25+31+34)
=48*90=4320
2.24.25+3.31.16+6.2.8.17
\(\text{2.24.25+3.31.16+6.2.8.17}\)
\(=\text{2.6.4.25+3.31.16+6.16.17}\)
\(=\text{12.100+16.3(31+2.17)}\)
\(=\text{1200+48(31+34)}=1200+48.65=1200+3120=4320\)
áp dụng tính chất phép cộng và phép nhân để tính nhanh:
a, 86+357+14 b,25.13.4 c,28.64+28.36
a) 86 + 357 + 14 = (86 + 14) + 357
= 100 + 357
= 457
b) 25 . 13 . 4 = (25 . 4) . 13
= 100 . 13
= 1300
c) 28 . 64 + 28 . 36 = 28 . (64 + 36)
= 28 . 100
=2800
a) 86 + 357 + 14
= ( 86 + 14 ) + 357
= 100 + 537
= 637
b)25 . 13 . 4
= ( 25 . 4 ) . 13
= 100 . 13
= 1300
c) 28 . ( 64 + 36 )
= 28 . 100
= 2800
a (86+14)+357=100+357=457
b 25.13.4=(25.4).13=100.13=1300
c 28.64+28.36=28.(64+36)=28.100=2800
tính hợp lý -259+(-74)+581+259+ ( -26) +(-81)
Tính hợp lý nhất
=(-259+259)+[(-74)+(-26)]+(-81+581)
=0+(-100)+500
=400
= -259 + 259 - 74 - 26 + 581 + 259 - 81
= 0 - 100 + 840 - 81
= 659
Tính hợp lý: 1 13/15.0,75-(104/195+25%).24/47-3 12/13:3
Tính hợp lý: 2 3/4.(-0,4)-1 3/5.2,75+(-1,2):4/11
\(1\frac{13}{15}.0,75-\left(\frac{104}{195}+25\%\right).\frac{24}{47}-3\frac{12}{13}:3\)
\(=\frac{28}{15}.\frac{3}{4}-\left(\frac{8}{15}+\frac{1}{4}\right).\frac{8}{9}-\frac{51}{13}.\frac{1}{3}\)
\(=\frac{7}{5}-\left(\frac{32}{60}+\frac{15}{60}\right).\frac{8}{9}-\frac{17}{13}\)
\(=\frac{7}{5}-\frac{47}{60}.\frac{8}{9}-\frac{17}{13}\)
\(=\frac{7}{5}-\frac{94}{135}-\frac{17}{13}\)
\(=\frac{-212}{351}\)
Tự quy đồng
\(2\frac{3}{4}.\left(-0,4\right)-1\frac{3}{5}.2,75+\left(-1,2\right):\frac{4}{11}\)
\(=\frac{11}{4}.\frac{-2}{5}-\frac{8}{5}.\frac{11}{4}-\frac{6}{5}.\frac{11}{4}\)
\(=\frac{11}{4}.\left(\frac{-2}{5}-\frac{8}{5}-\frac{6}{5}\right)\)
\(=\frac{11}{4}.\frac{-16}{5}\)
\(=\frac{-44}{5}=-8\frac{4}{5}\)