\(\left(4-\dfrac{2}{5}\right)+\dfrac{16}{-24}\\ =\left(\dfrac{4.5-2}{5}\right)-\dfrac{2}{3}\\ =\dfrac{20-2}{5}-\dfrac{2}{3}\\ =\dfrac{18}{5}-\dfrac{2}{3}\\ =\dfrac{18.3-2.5}{15}\\ =\dfrac{44}{15}\)
1. (-39)+14+26+39
2. (-54)+16+(-6)+54
3. 45+23+(-35)+(-23)
4. 45.17-5.9.7
5. 24.(16-5)-16.(24-5)
Bài 2: Tính hợp lý
1/ (-105). 47 -105. 53; 2/ 45 – 5. (12 + 9)
3/ 24. (16 – 5) – 16. (24 - 5) 4/ 29. (19 – 13) – 19. (29 – 13)
5/ 31. (-18) + 31. ( - 81) – 31 6/ (-12).47 + (-12). 52 + (-12)
1) -145.(13 - 57) + 57.(10 -145)
2) 17.(15 - 16) + 16.( 17- 20)
3) -38.(25 - 4) + 25.(-4 + 38 )
4) 23.(145 - 17) - 145.(23 - 6)
5) 24.(15 - 4) + 4.(24 - 15)
6) 199.(15 - 17) - 199.(-17 + 5)
7) -39.(5 - 99) + 99.(10 - 39)
Tính nhanh :
a, 24 . 64 + 36 . 24 - 100 . 24
b, 5 . 4² - 16 : 2²
Tính hợp lí
1) -145.(13 - 57) + 57.(10 -145)
2) 17.(15 - 16) + 16.( 17- 20)
3) -38.(25 - 4) + 25.(-4 + 38 )
4) 23.(145 - 17) - 145.(23 - 6)
5) 24.(15 - 4) + 4.(24 - 15)
6) 199.(15 - 17) - 199.(-17 + 5)
7) -39.(5 - 99) + 99.(10 - 39)
Tính hợp lí :
1/ 35 . 18 - 5 . 7 . 28
2/ 45 - 5. (12 + 9 )
3/ 24. ( 16 - 5 ) - 16. ( 24 - 5 )
4/ 13. ( 23 + 22 ) - 3. ( 17 + 28 )
a) 7*5^2 - 6*4^2
b)16*24+76*16+(-1600)
TÍNH NHANH
1) 24.( 16-5) -16.(24-5)
2)31.(-18)+31.(-18)-31
3) 13.(23+22) - 3.(17+28)
4) 19.25+9.95+19.30
a.4^8.4^4
b.5^12 . 7-5^11 . 10
c.2^20 . 15+2^10 . 85
d.27^16 : 9^10
e.125^3 :25^4
f.24^4 : 3^4 - 32^12: 16^12
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