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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.$x+1+(-1\dfrac23)=3:(-2)$

$\to x+1-(1\dfrac23)=3:(-2)$

$\to x+1-(1+\dfrac23)=\dfrac{3}{-2}$

$\to x+1-1-\dfrac23=-\dfrac{3}{2}$

$\to x-\dfrac23=-\dfrac32$

$\to x=-\dfrac56$

$\to x+1-(1+\dfrac23)=\dfrac{3}{-2}$