Tính một cách hợp lí:
a) 17.[29 - (- 111)] + 29.(- 17);
b) 19.43 + (- 20).43 - (- 40).
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\(a.\)
\(\dfrac{27}{13}-\dfrac{106}{111}+-\dfrac{5}{111}=\dfrac{27}{13}-\dfrac{106}{111}-\dfrac{5}{111}=\dfrac{27}{13}-\left(\dfrac{106+6}{111}\right)=\dfrac{27}{13}-1=\dfrac{14}{13}\)
\(b.\)
\(\dfrac{12}{11}-\dfrac{-7}{19}+\dfrac{12}{19}=\dfrac{12}{11}+\dfrac{7}{19}+\dfrac{12}{19}=\dfrac{12}{11}+1=\dfrac{23}{11}\)
\(c.\)
\(\dfrac{5}{17}-\dfrac{25}{31}+\dfrac{12}{17}+-\dfrac{6}{31}=\left(\dfrac{5}{17}+\dfrac{12}{17}\right)-\left(\dfrac{25}{31}+\dfrac{6}{31}\right)=1-1=0\)
a) \(\dfrac{27}{13}-\dfrac{106}{111}+\dfrac{-5}{111}=\dfrac{27}{13}+\left(\dfrac{-106}{111}+\dfrac{-5}{111}\right)=\dfrac{27}{13}+-1=\dfrac{14}{13}\)
b) \(\dfrac{12}{11}-\dfrac{-7}{19}+\dfrac{12}{19}=\dfrac{12}{11}+\left(\dfrac{7}{19}+\dfrac{12}{19}\right)=\dfrac{12}{11}+1=\dfrac{23}{11}\)
c)\(\dfrac{5}{17}-\dfrac{25}{31}+\dfrac{12}{17}+\dfrac{-6}{31}=\left(\dfrac{5}{17}+\dfrac{12}{17}\right)+\left(\dfrac{-25}{31}+\dfrac{-6}{31}\right)=1+-1=0\)
a) 4.(1 930 + 2 019) + 4.(-2 019)
= 4.(1 930 + 2 019 - 2 019)
= 4.1 930
= 7 720
b) (-3).(-17) + 3.(120 - 17)
= 3.17 + 3.(120 - 17)
= 3.(17 + 120 - 17)
= 3.120
= 360
a) 12 + 13 + 14 - 15 - 16 - 17
= (12 - 15) + (13 - 16) + (14 - 17)
= (-3) + (-3) + (-3) = -9
b) (35 - 17) - (25 - 7 + 22)
= 35 - 17 - 25 + 7 - 22
= (35 - 25) - (17 - 7) - 22
= 10 - 10 - 22 = -22
\(a)\left(-17\right)+\left(-23\right)+44=-40+44=4\)
\(b)\left(-39\right)+\left(-16\right)+39=\left[\left(-39\right)+39\right]+\left(-16\right)=0+\left(-16\right)=-16\)
\(a,\left(4+32+6\right)+\left(10-32-2\right)\\ =\left(10+32\right)+\left(10-32-2\right)\\ =10+32+10-32-2\\ =20-2\\ =18\\ b,300:4+300:6-25\\ =300:\left(4+6\right)-25\\ =300:10-25\\ =30-25\\ =5\\ c,17.\left[29-\left(-111\right)\right]+29.\left(-17\right)\\ =17.\left(29+111\right)+29.\left(-1\right).17\\ =17.\left(29+111-29\right)\\ =17.111=1887\\ d,19.43+\left(-20\right).43-\left(-40\right)\\ =19.43+\left(-20\right).43+40\\ =43.\left(19-20\right)+40\\ =-43+40\\ =-3\)
17[21-(-111)]+17[29-121]=17.132+17.(-92)=17.[132+(-92)]=17.40=680
a) Ta có: \(17\cdot\left[29-\left(-111\right)\right]+29\cdot\left(-17\right)\)
\(=17\cdot\left[29+111-29\right]\)
\(=17\cdot111=1887\)
b) Ta có: \(19\cdot43+\left(-20\right)\cdot43-\left(-40\right)\)
\(=43\cdot\left(19-20\right)+40\)
\(=-43+40=-3\)
Sao Nguyễn Lê Phước Thịnh lm khác bn ??? Ai sai