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A) =(5+(-15))+(9+(-19))+(-11)+(13+17)+(21+(-23))
=(-10)+(-10)+(-11)+20+(-2)
=((-10)+(-10))+(-11)+(-2)+20
=(-20)+(-11)+20+(-2)
=((-20)+20)+((-11)+(-2))
=0+(-13)=-13
B) doi ti !!!!! Tich cho mik nha
\(54:3^1+6.5^2\)
\(=54:3+6.25\)
\(=18+150\)
\(=168\)
\(---------\)
\(11-13+15-17+19-21+23-25\)
\(=\left(11-13\right)+\left(15-17\right)+\left(19-21\right)+\left(23-25\right)\)
\(=\left(-2\right)+\left(-2\right)+\left(-2\right)+\left(-2\right)\)
\(=\left(-2\right).4\)
\(=-8\)
Bài 1:
a; \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{7}{21}\) + (- \(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)
= \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{1}{3}\) -\(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\) - \(\dfrac{5}{8}\)
= (\(\dfrac{5}{18}\) - \(\dfrac{10}{36}\)) + (\(\dfrac{8}{19}\) + \(\dfrac{11}{19}\)) - (\(\dfrac{1}{3}\) - \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)
= (\(\dfrac{5}{18}\) - \(\dfrac{5}{18}\)) + \(\dfrac{19}{19}\) - 0 - \(\dfrac{5}{8}\)
= 0 + 1 - \(\dfrac{5}{8}\)
= \(\dfrac{3}{8}\)
b; \(\dfrac{1}{13}\) + (\(\dfrac{-5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\)) - (\(\dfrac{12}{17}\) - \(\dfrac{5}{18}\) + \(\dfrac{7}{5}\))
= \(\dfrac{1}{13}\) - \(\dfrac{5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{12}{17}\) + \(\dfrac{5}{18}\) - \(\dfrac{7}{5}\)
= (\(\dfrac{1}{13}\) - \(\dfrac{1}{13}\)) + (\(\dfrac{12}{17}\) - \(\dfrac{12}{17}\)) + (-\(\dfrac{5}{18}\) + \(\dfrac{5}{18}\)) - \(\dfrac{7}{5}\)
= 0 + 0 + 0 - \(\dfrac{7}{5}\)
= - \(\dfrac{7}{5}\)
Bài 1 c;
\(\dfrac{15}{14}\) - (\(\dfrac{17}{23}\) - \(\dfrac{80}{87}\) + \(\dfrac{5}{4}\)) + (\(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\))
= \(\dfrac{15}{14}\) - \(\dfrac{17}{23}\) + \(\dfrac{80}{87}\) - \(\dfrac{5}{4}\) + \(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\)
= (\(\dfrac{15}{14}-\dfrac{15}{14}\)) + (\(-\dfrac{17}{23}+\dfrac{17}{23}\)) - (\(\dfrac{5}{4}\) - \(\dfrac{1}{4}\)) + \(\dfrac{80}{87}\)
= 0 + 0 - 1 + \(\dfrac{80}{87}\)
= - \(\dfrac{7}{87}\)
A=[(1+9)+(3+7)+(5+15)+(11+13)].2
A=[10+10+20+24].2
A=64.2
A=128
B=(17+23)+(19+21)+(23+27)+(25+29)
B=40+40+50+54
B=tự tính
A=(1+9)+(3+7)+(5+15)+(7+13)+(11.2)
A=10+10+10+10+22
A=40+22
A=62
mình làm câu A thôi nhé
A = 1 - \(\dfrac{5}{6}\)+\(\dfrac{7}{12}\)-\(\dfrac{9}{20}\)+\(\dfrac{11}{30}\)-\(\dfrac{13}{42}\)+\(\dfrac{15}{56}\) - \(\dfrac{17}{72}\)+\(\dfrac{19}{90}\)+\(\dfrac{23}{132}\)-\(\dfrac{25}{156}\)
A = 1 - \(\dfrac{5}{2.3}\)+\(\dfrac{7}{3.4}\)-\(\dfrac{9}{4.5}\)+\(\dfrac{11}{5.6}\)-\(\dfrac{13}{6.7}\)+\(\dfrac{15}{7.8}\)-\(\dfrac{17}{8.9}\)+\(\dfrac{19}{9.10}\)+\(\dfrac{23}{11.12}\)-\(\dfrac{25}{12.13}\)
A = 1 - \(\dfrac{1}{2}-\dfrac{1}{3}\)+\(\dfrac{1}{3}+\dfrac{1}{4}\)-\(\dfrac{1}{4}-\dfrac{1}{5}\)+...+\(\dfrac{1}{11}+\dfrac{1}{12}\)- \(\dfrac{1}{12}-\dfrac{1}{13}\)
A = 1 - \(\dfrac{1}{2}\) - \(\dfrac{1}{13}\)
A = \(\dfrac{1}{2}\) - \(\dfrac{1}{13}\)
A = \(\dfrac{11}{26}\)
a)54 : 33 + 6.52
= 54 : 27 + 6.25
= 2 + 150
= 152
b) 45.26 + 45.74 - 1500
= 45.(26 + 74) - 1500
= 45.100 - 1500
= 4500 - 1500
= 3000
c) 125 + 132 + (-125) + (-21)
= [125 + (-125)] + [132 + (-21)]
= 0 + 111
= 111
d) 11 - 13 + 15 - 17 + 19 - 21 + 23 - 25
= -2 + (-2) + (-2) + (-2)
= (-4) + (-2) + (-2)
= (-8)
1+2+3+4+5+6+7+8+9+10=55
11+12+13+14+15+16+17+18+19+20=155
1+2+3+4+5+6+7+8+9+10+11+12+13+14 +15+16+17+18+19+20+21+22+23+24+25+26+27+28+29+30-50-53=362
=-2+-2+-2+25=-8+25=17
13-15+17-19+21-23+25
=13+(-15)+17+(-19)+21+(-23)+25
=[(-23)+13]+[(-15)+25]+17+(-19)+21
=-10+10+19
=[(-10)+10]+19
=0+19
=19