hiện phép tính (tính hợp lý nếu có thể).
) 17 + 15 + (- 27)
b) 13.75+25.13-300
c) 80 - (4.5 ^ 2 - 5.2 ^ 3) + 2021 ^ 0
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Câu 9
a) 2/15 + (-3/5)
= 2/15 - 3/5
= 2/15 - 9/15
= -7/15
b) -5/7 + 3/7 . (-2/9)
= -5/7 - 2/21
= -15/21 - 2/21
= -17/21
c) 5/16 - (7/15 - 3/16) + 17/30
= 5/16 - 7/15 + 3/16 + 17/30
= (5/16 + 3/16) + (17/30 - 14/30)
= 1/2 + 1/10
= 5/10 + 1/10
= 6/10
= 3/5
\(a,\dfrac{2}{15}+\left(-\dfrac{3}{5}\right)\\ =\dfrac{2}{15}-\dfrac{3}{5}\\ =\dfrac{2}{15}-\dfrac{9}{15}\\ =-\dfrac{7}{15}\\ b,-\dfrac{5}{7}+\dfrac{3}{7}\times\left(-\dfrac{2}{9}\right)\\ =-\dfrac{5}{7}-\dfrac{2}{21}\\ =-\dfrac{15}{21}-\dfrac{2}{21}\\ =-\dfrac{17}{21}\\ c,\dfrac{5}{16}-\left(\dfrac{7}{15}-\dfrac{3}{16}\right)+\dfrac{17}{30}\\ =\dfrac{5}{16}-\dfrac{7}{15}+\dfrac{3}{16}+\dfrac{17}{30}\\ =\left(\dfrac{5}{16}+\dfrac{3}{16}\right)-\left(\dfrac{17}{15}+\dfrac{17}{30}\right)\\ =\dfrac{1}{2}-\dfrac{17}{10}\\ =\dfrac{5}{10}-\dfrac{17}{10}\\ =-\dfrac{6}{5}.\)
A= \(\dfrac{11}{9}\).\(\dfrac{-3}{2}\)- \(\dfrac{11}{9}\).\(\dfrac{15}{2}\)+(2021)0
= \(\dfrac{11}{9}\)(\(\dfrac{-3}{2}\)-\(\dfrac{15}{2}\)) + 1
= \(\dfrac{11}{9}\)(-9) + 1
= -11 + 1
= -10
Lần sau bn ko đc phép chuyển \(\left(-2021\right)^0\) sang \(\left(2021\right)^0\) đou nha
a, 5\(\dfrac{4}{27}\) + \(\dfrac{6}{23}\) + 0,25 - \(\dfrac{4}{27}\) + \(\dfrac{17}{23}\)
= 5 + (\(\dfrac{4}{27}\) - \(\dfrac{4}{27}\)) + (\(\dfrac{6}{23}\) + \(\dfrac{17}{23}\)) + 0,25
= 5 + 1 + 0,25
= 6,25
b, 16.(\(\dfrac{1}{2}\))3 - \(\dfrac{3}{5}\): 0,75
= 16.\(\dfrac{1}{8}\) - 0,8
= 2 - 0,8
= 1,2
(-12) + (-18)
= -30
------------------
(-90) + 27 + (-10) + 73
= [(-90) + (-10) + (27 + 73)
= -100 + 100
= 0
---------------------------------
25 . (-5) . (-4)
= 25 . (-4) . (-5)
= -100 . (-5)
= 100 . 5
= 500
----------------------------------------
(-15) . 40 : 6
= [(-15) . 40] : 6
= (-600) : 6
= -100
-----------------------------------
(-27) . 58 + (-27) . 42
= (-27) . (58 + 42)
= (-27) . 100
= -2700
a) 17 + 15 + (-27)
= (17 - 27) + 15
= -10 + 15
= 5
b) 13.75 + 25.13 - 300
= 13.(75 + 26) - 300
= 13.100 - 300
= 1300 - 300
= 1000
c) 80 - (4.5² - 5.2³) + 2021⁰
= 80 - (4.25 - 5.8) + 1
= 80 - (100 - 40) + 1
= 80 - 60 + 1
= 20 + 1
= 21