Đáp án:

 

Giải thích các bước giải:

a) 1/6+ -5/6

= 1+(-5)/6=-4/6=-2/3

b) -3/-4 + 5/4

= 3/4+5/4

= 3+5/4

= 8/4=2

c) 7/24+ -5/36

7/24=21/72 

-5/36= -10/72

=> 7/24+ -5/36 = 21/72 + -10/72

                            = 11/72

d) 15/-21 +   -18/24

15/-21=-15/21

=> -15/21= -120/168

=> -18/24= -126/168

Vậy, 15/-21+ -18/24= -120/168+ -126/168= -246/168

                                                                      = -41/28

e) -7/12 + 3

=> -7/12 + 36/12

= -7+36/12

= -29/12

Chúc bạn học tốt nhé!

Đáp án + Giải thích các bước giải:

$\text{BÀI TẬP }$

$\text{a) $\dfrac{1}{6}$ + $\dfrac{- 5}{6}$}$

$\text{= $\dfrac{1 + (- 5)}{6}$}$

$\text{= $\dfrac{- 4}{6}$}$

$\text{= $\dfrac{-2}{3}$}$

$\text{b) $\dfrac{-3 }{-4}$ + $\dfrac{5}{4}$}$

$\text{= $\dfrac{3}{4}$ + $\dfrac{5}{4}$}$

$\text{= $\dfrac{3 + 5}{4}$}$

$\text{= $\dfrac{8}{4}$}$

$\text{= 2}$

$\text{c) $\dfrac{7}{24}$ + $\dfrac{- 5}{36}$}$

$\text{= $\dfrac{21}{72}$ + $\dfrac{-10}{72}$}$

$\text{= $\dfrac{11}{72}$}$

$\text{d) $\dfrac{15}{- 21}$ + $\dfrac{- 18}{24}$}$

$\text{= $\dfrac{- 5}{7}$ + $\dfrac{-3}{4}$}$

$\text{= $\dfrac{-20}{28}$ + $\dfrac{-21}{28}$}$

$\text{= $\dfrac{-41}{28}$}$

$\text{e) $\dfrac{-7}{12}$ + 3}$

$\text{= $\dfrac{-7}{12}$ + $\dfrac{36}{12}$}$

$\text{= $\dfrac{29}{12}$}$

Cho mk xin ctlhn ạ !

@vincent