a) 17 4/10

b ) 9 35/100

CHỗ còn lại tự làm nhé !

\(y\times\dfrac{2}{3}=\dfrac{1}{4}+\dfrac{1}{1}\)

\(y\times\dfrac{2}{3}=\dfrac{1}{4}+\dfrac{4}{4}\)

\(y\times\dfrac{2}{3}=\dfrac{5}{4}\)

\(y=\dfrac{5}{4}:\dfrac{2}{3}\)

\(y=\dfrac{5}{4}\times\dfrac{3}{2}\)

\(y=\dfrac{15}{8}\)

Áp dụng định lý Pi-ta-go trong tam giác vuông

a, 6 dm; 10 dm; 8 dm

Do 6²+8²=10² nên là tam giác vuông

b, 5cm; 9 cm; 7 cm 

Do 5²+7²\(\ne\)9² nên không phải là tam giác vuông

c, 4 m ;  6 m ; bình phương 52 m

Do 4²+6²=\(\sqrt{52}^2\)nên là tam giác vuông

nhiều quá :((

\(a,2\left(x-5\right)-3\left(x+7\right)=14\)

\(2x-10-3x-21=14\)

\(-x-31=14\)

\(-x=45\)

\(x=45\)

\(b,5\left(x-6\right)-2\left(x+3\right)=12\)

\(5x-30-2x-6=12\)

\(3x-36==12\)

\(3x=48\)

\(x=16\)

\(c,3\left(x-4\right)-\left(8-x\right)=12\)

\(3x-12-8+x=0\)

\(4x-20=0\)

\(4x=20\)

\(x=5\)

Cố nốt nha bn ! 

cảm ơn, bn nha:)))

mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???

d, \(-7\left(3x-5\right)+2\left(7x-14\right)=28\)

\(\Leftrightarrow-21x+35+14x-28=28\Leftrightarrow-7x=21\Leftrightarrow x=-3\)

e, \(5\left(3-2x\right)+5\left(x-4\right)=6-4x\)

\(\Leftrightarrow15-6x+5x-20=6-4x\Leftrightarrow-5-x=6-4x\)

\(\Leftrightarrow-11+3x=0\Leftrightarrow x=\frac{11}{3}\)

f, \(-5\left(2-x\right)+4\left(x-3\right)=10x-15\)

\(\Leftrightarrow-10+5x+4x-12=10x-15\Leftrightarrow-22+9x=10x-15\)

\(\Leftrightarrow-7-x=0\Leftrightarrow x=-7\)

\(\frac{5}{12}\times\frac{8}{15}=\frac{2}{9}\)

\(2\frac{7}{15}\times5\frac{3}{14}=\frac{37}{15}\times\frac{73}{14}=\frac{2701}{210}\)

\(\frac{4}{9}:\frac{2}{5}=\frac{10}{9}\)

\(3\frac{3}{11}:2\frac{4}{9}=\frac{36}{11}:\frac{22}{9}=\frac{162}{121}\)

\(x\times\frac{2}{5}=\frac{6}{21}\)

\(x=\frac{6}{21}:\frac{2}{5}\)

\(x=\frac{5}{7}\)

\(x:\frac{3}{5}=\frac{7}{25}\)

\(x=\frac{7}{25}\times\frac{3}{5}\)

\(x=\frac{21}{125}\)

a) x + 2 = - 9 - 11

   x + 2  = - 20

        x   = - 20 - 2

         x  = - 22

Vậy x = - 22

b) x - 2 = - 6 + 17

   x - 2  = 11

        x  = 11 + 2

        x  = 13

 Vậy x = 13

e ) l x - 5 l = 5

=> \(\orbr{\begin{cases}x-5=5\\x-5=-5\end{cases}}\)=> \(\orbr{\begin{cases}x=5+5\\x=-5+5\end{cases}}\)=>\(\orbr{\begin{cases}x=10\\x=0\end{cases}}\)

Vậy x thuộc { 0 ; 10 }

mn. giúp em nha 

\(a.\dfrac{6}{5}=\dfrac{18}{x}\Rightarrow x=\dfrac{18\cdot5}{6}=15\\ \text{Vậy}\text{ }x=15.\)

\(b.\dfrac{3}{4}=\dfrac{-21}{x}\Rightarrow x=\dfrac{-21\cdot4}{3}=28\\ \text{ }\text{ }\text{ }\text{ }\text{Vậy }x=28.\)

\(c.\dfrac{x}{4}=\dfrac{21}{28}\Rightarrow x=\dfrac{21\cdot4}{28}=3\\ \text{Vậy }x=3.\)

\(d.\dfrac{-8}{2x}=\dfrac{3}{-9}\Rightarrow x=\dfrac{-8\cdot\left(-9\right)}{3}:2=12\\ \text{Vậy }x=12.\)

\(e.\dfrac{-4}{11}=\dfrac{x}{22}=\dfrac{40}{z}\\ \Rightarrow x=\dfrac{-4\cdot22}{11}=-8\\ \Rightarrow z=\dfrac{22\cdot40}{-8}=-110\\ \text{Vậy }x=-8;z=-110.\)

\(f.\dfrac{-3}{4}=\dfrac{x}{20}=\dfrac{21}{y}\\ \Rightarrow x=\dfrac{-3\cdot20}{4}=-15\\ \Rightarrow y=\dfrac{21\cdot20}{-15}=-28\\ \text{Vậy }x=-15;y=-28.\)

\(g.\dfrac{-4}{8}=\dfrac{x}{-10}=\dfrac{-7}{y}=\dfrac{z}{-24}\\ \Rightarrow x=\dfrac{-4\cdot\left(-10\right)}{8}=5\\ \Rightarrow y=\dfrac{-7\cdot\left(-10\right)}{5}=14\\ \Rightarrow z=\dfrac{-7\cdot\left(-24\right)}{14}=12\\ \text{Vậy }x=5;y=14;z=12.\)

\(h.\dfrac{x}{4}=\dfrac{9}{x}\\ \Rightarrow x\cdot x=9\cdot4\\ \Rightarrow x\cdot x=36\\ \Rightarrow x\cdot x=6\cdot6\\ \text{Vậy }\text{cả hai }x=6.\)

a,x+5=(-6)+2

x+5=(-4)

x=(-4)-5

x=-9

b,x-7=(-8)

x=(-8)+7

x=-1

c,x-(-4)=15

x+4=15

x=15-4

x=11

d,-12+x=3

x=3-(-12)

x=3+12

x=15

e,x+(-3)=6

x=6-(-3)

x=6+3

x=9

g,8-x=(-2)-(-6)

8-x=(-2)+6

8-x=4

x=8-4

x=4

h,x-10=(-5)+(-9)

x-10=(-14)

x=(-14)+10

x=-4