tính hợp lí:2/9 +-1/7 +26/35 + 8/45
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Lời giải:
$(\frac{2}{9}-\frac{1}{7})-(\frac{26}{-35}+\frac{-8}{45})$
$=\frac{2}{9}-\frac{1}{7}+\frac{26}{35}+\frac{8}{45}$
$=(\frac{2}{9}+\frac{8}{45})+(\frac{26}{35}-\frac{1}{7})$
$=(\frac{10}{45}+\frac{8}{45})+(\frac{26}{35}-\frac{5}{35})$
$=\frac{18}{45}+\frac{21}{35}=\frac{2}{5}+\frac{3}{5}=\frac{5}{5}=1$
35.13+35.17+65.75-65.45
=35.(13+17)+65.(75-45)
=35.30+65.30
=30.(35+65)
=30.100
=3000
1/ 1+(-6)+11+(-16)+21+(-26)+31+(-36)
= -20
2/1+(-3)+2+8+(-7)+7+3+9+17+100+(-7)
=130
a: \(=5+\dfrac{1}{5}-\dfrac{2}{9}+\dfrac{2}{23}-\dfrac{3}{35}-\dfrac{5}{6}-8-\dfrac{2}{7}+\dfrac{1}{18}\)
\(=-3+\left(-\dfrac{2}{9}-\dfrac{5}{6}+\dfrac{1}{18}\right)+\left(\dfrac{1}{5}+\dfrac{2}{23}-\dfrac{3}{35}-\dfrac{2}{7}\right)\)
\(=-3+\dfrac{-12-45+1}{18}+\dfrac{7-10-3}{35}+\dfrac{2}{23}\)
\(=3-\dfrac{28}{9}+\dfrac{-6}{35}+\dfrac{2}{23}=\dfrac{-1417}{7245}\)
1) \(35.18-5.7.28\)
\(=35.18-35.28\)
\(=35.\left(18-28\right)\)
\(=35.\left(-10\right)\)
\(=-350\)
2) \(45-5.\left(12+9\right)\)
\(=45-60-45\)
\(=\left(45-45\right)-60\)
\(=0-60\)
\(=-60\)
3) \(24.\left(16-5\right)-16.\left(24-5\right)\)
\(=\left(384-120\right)-\left(384-120\right)\)
\(=264-264\)
\(=0\)
4) \(13.\left(23+22\right)-3.\left(17+28\right)\)
\(=13.45-3.45\)
\(=\left(13-3\right).45\)
\(=10.45\)
\(=450\)
tk ủng hộ nha!!!!!!!!1
1/ 35 . 18 - 5 . 7 . 28
= 35 . 18 - 35 . 28
= 35 . (18 - 28)
= 35 . (-10)
= -350
2/ 45 - 5 . (12 + 9)
= 5 . 9 - 5 . 12 + 5 . 9
= 5 . (9 - 12 + 9)
= 5 . 6
= 30
3/ 24 . (16 - 5) - 16 . (24 - 5)
= 24 . 16 - 24 . 5 - 16 . 24 - 16 . 5
= (24 . 16 - 16 . 24) - (24 . 5 - 16 . 5)
= 0 - [5 . (24 - 16)]
= 0 - [5 . 8]
= 0 - 40
= -40
4/ 13 . (23 + 22) - 3 . (17 + 28)
= 13 . 45 - 3 . 45
= 45 . (13 - 3)
= 45 . 10
= 450
A, 35×18-5×7×28 = 35x18-5x7x28
= 35x18-35x28
= 35(18-28)
= 35.(-10)
= -350
B, 45-5× (12+9) = 45-5x12-5x9
= 45-60-45
=(45-45)-60
= 0-60
=-60
= -350
A, 35×18-5×7×28 = 35x18-5x7x28
= 35x18-35x28
= 35(18-28)
= 35.(-10)
= -350
B, 45-5× (12+9) = 45-5x12-5x9
= 45-60-45
=(45-45)-60
= 0-60
=-60
\(\frac29+\left(-\frac17\right)+\frac{26}{35}+\frac{8}{45}=1\)