các bn lm đến đâu cx dc miễn là lm hộ mk cái ạ, ai đang lm vào nhắn tin vs mk để mk bít nha

a; \(-\dfrac{8}{3}+\dfrac{7}{5}-\dfrac{71}{15}< x< -\dfrac{13}{7}+\dfrac{19}{14}-\dfrac{7}{2}\)

              -\(\dfrac{19}{15}\) - \(\dfrac{71}{15}\) < \(x\) < -\(\dfrac{1}{2}\) - \(\dfrac{7}{2}\)

              -6 < \(x\) < -4

             vì \(x\) \(\in\) Z nên \(x\) = -5

110 nha k nha nha nha

5+6+7+8+9+10+11+12+13+14+15

=(15+5)+(14+6)+(13+7)+(12+8)+(11+9)+10

=20+20+20+20+20+10

=5.20+10

=100+10

=110

444 nha

k nha

=435nha bạn

x+(x+1) +(x+2) + ... + (x+14 )=14

(x+x+x+...+x) + (1+2+3+4+ ...+14)=14

15x + [(14-1):1+1].(1+14) :2=14

15x + 105=14

15x=-91

suy ra x=-91/15

Đặt :

\(A=\)\(\dfrac{1}{5}+\dfrac{1}{13}+\dfrac{1}{14}+\dfrac{1}{15}+\dfrac{1}{61}+\dfrac{1}{62}+\dfrac{1}{63}\)

\(A=\dfrac{1}{5}+\left(\dfrac{1}{13}+\dfrac{1}{14}+\dfrac{1}{15}\right)+\left(\dfrac{1}{61}+\dfrac{1}{62}+\dfrac{1}{63}\right)\)

Ta thấy :

\(\dfrac{1}{13}+\dfrac{1}{14}+\dfrac{1}{15}< \dfrac{1}{12}+\dfrac{1}{12}+\dfrac{1}{12}\)

\(\dfrac{1}{61}+\dfrac{1}{62}+\dfrac{1}{63}< \dfrac{1}{60}+\dfrac{1}{61}+\dfrac{1}{62}\)

\(\Rightarrow A< \dfrac{1}{5}+\left(\dfrac{1}{12}+\dfrac{1}{12}+\dfrac{1}{12}\right)+\left(\dfrac{1}{60}+\dfrac{1}{60}+\dfrac{1}{60}\right)\)

\(\Rightarrow A< \dfrac{1}{5}+\dfrac{1}{12}.3+\dfrac{1}{60}.3\)

\(\Rightarrow A< \dfrac{1}{5}+\dfrac{1}{4}+\dfrac{1}{20}\)

\(\Rightarrow A< \dfrac{10}{20}=\dfrac{1}{2}\)

\(\Rightarrow A< \dfrac{1}{2}\rightarrowđpcm\)

\(\left(\frac{5}{13}-\frac{9}{14}\right)-\left(2+-\frac{21}{13}-\frac{5}{-14}\right)\)

\(=-\frac{47}{182}-\frac{135}{182}\)

\(=-1\)

tíc mình nha

(5/13 −9/14 )−(2+−21/13 −5/−14 )

=−47/182 −135/182 

=−1

12 x 13 = 156

13 x 14 = 182

25 x 4 = 100

64 x 5 =320

12 x13= 156

13x 14= 182

25x4= 100

64x5= 320

Tk mk nhá

3/17 - 5/13 - 18/35 + 14/17 + 17/-35 - 8/13

=(3/17+14/17)+(-5/13-8/13)+(-18/35+17/35)

=1+(-1)+(-1/35)

=-1/35

Chúc bn học tốt

\(\frac{3}{17}-\frac{5}{13}-\frac{18}{35}+\frac{14}{17}\)\(+\frac{17}{-35}-\frac{8}{13}\)

\(=\left(\frac{3}{17}+\frac{14}{17}\right)\)\(-\left(\frac{18}{35}-\frac{-17}{35}\right)\)\(-\left(\frac{5}{13}+\frac{8}{13}\right)\)

\(=1-1-1\)\(=0\)