12/13 + 2/7 + 8/13 + 6/13 + 5/7

= ( 2/7 + 5/7 ) + ( 12/13 + 8/13 + 6/13 )

= 1 + 2

= 3

=(12/13+8/13+6/13)+(2/7+5/7)=2+1=3

12/13+2/7+8/13+6/13+5/7

   =(12/13+8/13+6/13)+(2/7+5/7)

   =2+1

   =3 

a: =16-2+91=14+91=105

b: =9*5+8*10-27=45+53=98

c: =32+65-3*8=8+65=73

d; \(=5^3-10^2=125-100=25\)

e: \(=4^2-3^2+1=8\)

f: =9*16-16*8-8+16*4

=16(9-8+4)-8

=16*5-8

=72

a) \(2^4-50:25+13\cdot7\)

\(=2^4-2+91\)

\(=16-2+91\)

\(=14+91\)

\(=105\)

b) \(3^2\cdot5+2^3\cdot10-3^4:3\)

\(=9\cdot5+8\cdot10-3^3\)

\(=45+80-27\)

\(=98\)

c) \(2^5+5\cdot13-3\cdot2^3\)

\(=32+65-3\cdot8\)

\(=32+65-24\)

\(=73\)

d) \(5^{13}:5^{10}-5^2\cdot2^2\)

\(=5^{13-10}-\left(5\cdot2\right)^2\)

\(=5^3-10^2\)

\(=125-100\)

\(=25\)

e) \(4^5:4^3-3^9:3^7+5^0\)

\(=4^{5-3}-3^{9-7}+1\)

\(=4^2-3^2+1\)

\(=16-9+1\)

\(=8\)

f) \(3^2\cdot2^4-2^3\cdot4^2-2^3\cdot5^0+4^2\cdot2^2\)

\(=3^2\cdot4^2-2^3\cdot4^2-2^3\cdot1+4^2\cdot2^2\)

\(=4^2\cdot\left(3^2-2^3+2^2\right)-2^3\)

\(=4^2\cdot\left(9-8+4\right)-8\)

\(=16\cdot5-8\)

\(=72\)

a) \(\dfrac{-5}{9}-\dfrac{-5}{12}=\dfrac{-5}{9}+\dfrac{5}{12}=\dfrac{-20}{36}+\dfrac{15}{36}=-\dfrac{5}{36}\)

b) \(\dfrac{-5}{12}:\dfrac{15}{4}=\dfrac{-5}{12}\times\dfrac{4}{15}=\dfrac{-1}{9}\)

c) \(\dfrac{1}{13}\cdot\dfrac{8}{13}+\dfrac{5}{13}\cdot\dfrac{1}{13}-\dfrac{14}{13}=\dfrac{1}{13}\cdot\left(\dfrac{8}{13}+\dfrac{5}{13}\right)-\dfrac{14}{13}=\dfrac{1}{13}\cdot1-\dfrac{14}{13}=\dfrac{1}{13}-\dfrac{14}{13}=-1\)

a)=--5/36

b)=-1/9

c) =-1 

cách làm như trên

\(\dfrac{12}{13}\times\dfrac{13}{15}=\dfrac{12}{15}=\dfrac{4}{5}\)

`12/13+13/15` đề ntn phải ko ạ?

`=180/195+169/195`

`=349/195`

\(\dfrac{12}{15}\) ( triệt tiêu phần giống nhau là 13 )

-1300

-3600

1544

13.(-87)+(-13).13= 13.(-87+(-13))

                        = 13.(-100)

                        =-1300

13.(-87)+(-13).13

=13.[(-87)+(-13)]

=13.(-100)

=-1300

36.(-54)+92.(-18)

=36.(-54)+36.2.(-18)

=36.(-54)+36.(-36)

=36.[(-54)+(-36)]

=36.(-100)

=-3600

3/5+47/13-25/8+1/8-8/13+2/5 = 1 nhé!

     =>( \(\frac{3}{5}\)+ \(\frac{2}{5}\)) +  (\(\frac{47}{13}\)- \(\frac{8}{13}\)) - (\(\frac{25}{8}\)+ \(\frac{1}{8}\))

       => 1 + 3 - \(\frac{26}{8}\)

      => 4 - \(\frac{26}{8}\)

      => \(\frac{4}{1}\)- \(\frac{26}{8}\)

      => \(\frac{32-26}{8}\)

      => \(\frac{6}{8}\)

      => \(\frac{3}{4}\)

a)15.12-3.5.10=180-150=30(c1)

15.12-3.5.10=15.12-15.10=15.(12-10)=15.2=30(c2)

b) 45-9.(13+5)=45-9.18=45-162=-117

45-9.(13+5)=45-9.13-9.5=45-45-117=0-117=-117

c)c,29.(19-13)-19.(29-13)=29.19-29.13-19.29+19.13=29.19-19.29-29.13+19.13=0-(29.13-19.13)=0-((29-19).13)=0-(10.13)=0-130=-130

nhưng sao chỉ bằng có 124 thoi cậu giải rõ ra to tik cho

cach 2 cau c

c,29.(19-13)-19.(29-13)=29.6-19.16=174-304=-130

a, 45 x 46 + 45 x 45 - 30 - 15= 45x( 46+45) -30 -15= 45 x 91 - 30 - 15= 4095 - 30 - 15= 4050

b, 891 x 29 + 29 x 8+ 29= 29 x ( 891 + 8+ 1)= 29 x 900= 26100

c, 73 x ( 84+17) + 27 x (74+27)= 73 x 101 + 27 x 101= 101 x ( 73+27)= 101 x 100= 10100

d, chịu

d, đề bài= 13 x ( 99 + 2) + 13 x 1001+ 11 x 1300= 13 x 101 + 13 x 1001+ 13 x 1100= 13 x ( 101 + 1001 + 1100) = 13 x 2202= 28626