Đáp án:

Giải thích các bước giải:

1.

a) $\frac{2}{7}$ 

b) -$\frac{5}{9}$ 

c) $\frac{11}{-13}$ 

d) $\frac{14}{-5}$ 

2.

a) $\frac{-3}{11}$ 

b) $\frac{4}{-11}$ 

c) $\frac{-8}{15}$ 

d) $\frac{x}{-3}$ (x thuộc Z)

3.

a) $\frac{-2}{1}$ 

b) $\frac{13}{1}$ 

c) $\frac{-9}{1}$ 

d) $\frac{0}{1}$ 

e) $\frac{-25}{1}$ 

4.

a) x.21=6.7 ⇔ 21x =42 ⇔ x=2

b)-5.28=20.y ⇔ -140=20y ⇔ y=-7

c)-1.12=2z ⇔ -12=2z ⇔ z=-6

d)32x=8.(-28) ⇔ 32x=-224 ⇔ x=-7

e)3z=-4.15 ⇔ 3z=-60 ⇔ z=-20

f)3.(-24)=12y ⇔ -72=12y ⇔ y=-6

g)-5.63=9x ⇔ -315=9x ⇔ x=-35

h)7.y=-15.21 ⇔ 7y=-315 ⇔ y=-45

5.

a)$\frac{6}{-14}$ 

b)$\frac{2}{-10}$ 

c)$\frac{26}{-42}$ 

d)$\frac{52}{-102}$ 

e)$\frac{4}{5}$ 

f)$\frac{11}{3}$ 

g)$\frac{27}{14}$ 

h)$\frac{1}{23}$ 

6.

a)z.6=(-12).(-4) ⇔ 6z=48 ⇔ z=8

  8y=(-8).(-12) ⇔ 8y=96 ⇔ y=12

  x.12=15.(-8) ⇔ 12x = -120 ⇔ x=-10

b)-12x=16.15 ⇔ -12x=240 ⇔ x=-20

   -20y=15.(-24) ⇔ -20y=-360 ⇔ y=18

   (-24).(-z)=18.8 ⇔ 24z=144 ⇔ z=6

c)22x=-33.12 ⇔ 22x=-396 ⇔ x=-18

   12y=22.18 ⇔ 12y=396 ⇔ y=33

d)84y=(-35).(-36) ⇔ 84y=1260 ⇔ y=15

  15x=3.(-35) ⇔ 15x=-105 ⇔ x=-7

7. 

a)$\frac{2}{5}$ 

b)$\frac{7}{12}$ 

c)$\frac{-7}{9}$ 

d)$\frac{-1}{4}$ 

e)$\frac{1}{-6}$ 

f)$\frac{1}{-7}$ 

g)$\frac{1}{3}$ 

h)$\frac{2}{3}$ 

i)$\frac{9}{25}$ 

j)$\frac{-1}{6}$ 

k)$\frac{1}{-3}$ 

l)$\frac{3}{7}$ 

8. 

a)$\frac{-2}{5}$ = $\frac{-2.5}{5.5}$ = $\frac{-10}{25}$ 

$\frac{3}{25}$ = $\frac{3}{25}$

b)$\frac{-11}{120}$ = $\frac{-11}{120}$ 

$\frac{-7}{40}$ = $\frac{-7.3}{40.3}$ = $\frac{-21}{120}$

c)$\frac{1}{15}$ = $\frac{1}{15}$ 

-6 = $\frac{-6.15}{15}$ = $\frac{-90}{15}$ 

d) 2=$\frac{2.7}{7}$ = $\frac{14}{7}$ 

$\frac{-19}{7}$ = $\frac{-19}{7}$

e)$\frac{3}{4}$ =$\frac{3.3}{4.3}$ =$\frac{9}{12}$ 

$\frac{5}{-6}$ =$\frac{5.(-2)}{(-6).(-2)}$ =$\frac{-10}{12}$

f)$\frac{-15}{-28}$ =$\frac{(-15).(-15)}{(-28).(-15)}$ =$\frac{225}{420}$ 

$\frac{-17}{30}$ =$\frac{-17.4}{30.4}$=$\frac{-68}{120}$ 

g)$\frac{-31}{36}$= $\frac{-31.15}{36.15}$ =$\frac{-465}{540}$ 

$\frac{13}{-60}$ =$\frac{13.(-9)}{(-60).(-9)}$ =$\frac{-117}{540}$

h)$\frac{-4}{7}$ =$\frac{-4.9}{7.9}$ =$\frac{-36}{63}$ 

$\frac{8}{9}$ =$\frac{8.7}{9.7}$ =$\frac{56}{63}$

$\frac{-10}{21}$ =$\frac{-10.3}{21.3}$ =$\frac{-30}{63}$

i)$\frac{-3}{16}$ =$\frac{-3.3}{16.3}$ =$\frac{-9}{48}$ 

$\frac{5}{24}$ =$\frac{5.2}{24.2}$ =$\frac{10}{48}$

$\frac{-21}{56}$ =$\frac{-3}{8}$ =$\frac{-3.6}{6.8}$ =$\frac{-18}{48}$

j)$\frac{36}{64}$ =$\frac{9}{16}$ =$\frac{9.81}{16.81}$= $\frac{729}{1296}$ 

$\frac{-12}{81}$ =$\frac{-4}{27}$ =$\frac{-4.48}{27.48}$ =$\frac{-192}{1296}$

$\frac{-28}{162}$ =$\frac{-14}{81}$= $\frac{-14.16}{81.16}$ =$\frac{-224}{1296}$