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Giải thích các bước giải:
Bài 3:
a.$1\dfrac23+1+(-\dfrac14)$
$=\dfrac53+1-\dfrac14$
$=\dfrac83-\dfrac14$
$=\dfrac{32}{12}-\dfrac{3}{12}$
$=\dfrac{32-3}{12}$
$=\dfrac{29}{12}$
b.$-\dfrac32+(-1\dfrac23)+1$
$=-\dfrac32-(1\dfrac23)+1$
$=-\dfrac32-(1+\dfrac23)+1$
$=-\dfrac32-1-\dfrac23+1$
$=-\dfrac32-\dfrac23+1-1$
$=-3+0$
$=-3$
c.$-3\dfrac34-2$
$=-(3+\dfrac34)$
$=-3-\dfrac34-2$
$=-5-\dfrac34$
$=-(5+\dfrac34)$
$=-5\dfrac34$
d.$1\dfrac25-2\%+1\dfrac1{15}$
$=(1+\dfrac25)-\dfrac{2}{100}+(1+\dfrac1{15})$
$=1+\dfrac25-\dfrac{1}{50}+1+\dfrac1{15}$
$=2+\dfrac25-\dfrac1{50}+\dfrac1{15}$
$=2+\dfrac{20}{50}-\dfrac1{50}+\dfrac1{15}$
$=2+\dfrac{20-1}{50}+\dfrac1{15}$
$=2+\dfrac{19}{50}+\dfrac1{15}$
$=\dfrac{300}{150}+\dfrac{57}{150}+\dfrac{10}{150}$
$=\dfrac{300+57+10}{150}$
$=\dfrac{367}{150}$
e.$\dfrac37-\dfrac73+\dfrac5{21}$
$=\dfrac{9}{21}-\dfrac{49}{21}+\dfrac{5}{21}$
$=\dfrac{9-49+5}{21}$
$=\dfrac{-35}{21}$
$=-\dfrac53$
Bài 4:
a.$\dfrac32:(-1\dfrac14)=x-1$
$\to \dfrac32:\dfrac{-5}4=x-1$
$\to -\dfrac65=x-1$
$\to x=\dfrac{-1}5$
b.$x+1+(-1\dfrac23)=3:(-2)$
$\to x+1-(1\dfrac23)=3:(-2)$
$\to x+1-(1+\dfrac23)=\dfrac{3}{-2}$
$\to x+1-1-\dfrac23=-\dfrac{3}{2}$
$\to x-\dfrac23=-\dfrac32$
$\to x=-\dfrac56$
$\to x+1-(1+\dfrac23)=\dfrac{3}{-2}$
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