a: Ta có: \(\dfrac{x+6}{8}+\dfrac{x+8}{6}+\dfrac{x+1}{13}+3=0\)

\(\Leftrightarrow\dfrac{x+14}{6}+\dfrac{x+14}{6}+\dfrac{x+14}{13}=0\)

\(\Leftrightarrow x+14=0\)

hay x=-14

b) Ta có: \(\dfrac{x-5}{10}+\dfrac{x-7}{8}+\dfrac{x-1}{14}=3\)

\(\Leftrightarrow\dfrac{x-15}{10}+\dfrac{x-15}{8}+\dfrac{x-15}{14}=0\)

\(\Leftrightarrow x-15=0\)

hay x=15

\(/x-\frac{1}{2}/=\frac{1}{3}\\ =>\orbr{\begin{cases}x-\frac{1}{2}=\frac{1}{3}\\x-\frac{1}{2}=-\frac{1}{3}\end{cases}}\\ =>\orbr{\begin{cases}x=\frac{1}{3}+\frac{1}{2}\\x=-\frac{1}{3}+\frac{1}{2}\end{cases}}\\ =>\orbr{\begin{cases}x=\frac{5}{6}\\x=\frac{1}{6}\end{cases}}\)

\(a,|x-\frac{1}{2}|=\frac{1}{3}\)

\(\Rightarrow\orbr{\begin{cases}x-\frac{1}{2}=\frac{1}{3}\\x-\frac{1}{2}=-\frac{1}{3}\end{cases}\Rightarrow\orbr{\begin{cases}x=\frac{5}{6}\\x=\frac{1}{6}\end{cases}}}\)

\(b,\frac{14}{15}:\frac{9}{10}=x:\frac{3}{7}\)

\(\frac{28}{27}=x:\frac{3}{7}\)

\(x=\frac{4}{9}\)

\(c,\frac{6}{5}:8=\frac{2}{5}:x\)

\(\frac{3}{20}=\frac{2}{5}:x\)

\(x=\frac{8}{3}\)

\(d,3x-\frac{7}{8}=\frac{5}{2}\)

\(3x=\frac{27}{8}\)

\(x=\frac{9}{8}\)

\(D=4x^2-2x+3x\left(x-5\right)=4x^2-2x+3x^2-15x=7x^2-17x=7\left(-1\right)^2-17\left(-1\right)=24\)

\(E=x^{10}-2020x^9+2020x^8-2020x^7+...+2020x^2-2020x=x^9\left(x-2019\right)-x^8\left(x-2019\right)+x^7\left(x-2019\right)-...-x^2\left(x-2019\right)+x\left(x-2019\right)-x=x^9\left(2019-2019\right)-...+x\left(2019-2019\right)-2019=-2019\)

6 x 8 = 48

5 x 6 = 30 

8 x 10 = 80

12 x 2 = 24

10 x 15 = 150

48

30

80

24

150

pn nha nếu đung tk cho mk nha

6x8=48

5x6=30

8x10=80

12x2=24

10x15=150

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

- \(\dfrac{19}{6}+\dfrac{-15}{2}+\dfrac{11}{3}\) < \(x\) < - \(\dfrac{5}{4}\) + \(\dfrac{19}{12}\) - \(\dfrac{10}{3}\)

- \(\dfrac{32}{3}+\dfrac{11}{3}< x< \) \(\dfrac{1}{3}\) - \(\dfrac{10}{3}\)

-7 < \(x\) < - 3

Vì \(x\in\) Z nên \(x\in\) {-6;-5;-4}

tách nhỏ ra

\(\dfrac{6}{8}-\dfrac{2}{7}=\dfrac{42}{56}-\dfrac{16}{56}=\dfrac{26}{56}=\dfrac{13}{28}\)

\(a,\frac{7}{x}=\frac{x}{28}=>x\cdot x=28\cdot7=>x^2=196=>x^2=14^2\)\(=>x=14\)

\(b,\frac{10+x}{x+17}=\frac{3}{4}=>\left(10+x\right)\cdot4=\left(x+17\right)\cdot3=>40+x4=x3+51\)\(=>x4-x3=51-40=>x=11\)