\(\frac{9}{4}-y.\frac{5}{6}=\frac{1}{2}+\frac{2}{3}\)

\(\frac{9}{4}-y.\frac{5}{6}=\frac{7}{6}\)

\(y.\frac{5}{6}=\frac{9}{4}-\frac{7}{6}\)

\(y.\frac{5}{6}=\frac{13}{12}\)

\(y=\frac{13}{12}:\frac{5}{6}\)

\(y=\frac{13}{10}\)

9 / 4 - y x 5 / 6 = 1 / 2 + 2 / 3

9 / 4 - y x 5 / 6 = 7 / 6

          y x 5 / 6 = 13 /12

          y            = 13 /10

y.5 + y : 1/2 + y : 1/3 

= y.5 + y.2 + y.3

= y.(5 + 2 + 3)

= y.10 

y x 5 + y : 1/2 + y : 1/3

= y x 5 + y x 2/1 + y x 3/1

= y x 5 + y x 2 + y x 3

= y x ( 5 + 2 + 3 )

= y x 10

Bạn phải cho giá trị của biểu thức mới làm được chứ

y x 5 + (2 + 4 + 6 +...+ 18) = 270

=> y x 5 + (18 + 2) x 9 : 2 = 270 (Công thức tính tổng)

=> y x 5 + 20 x 9 : 2 = 270

=> y x 5 + 180 : 2 = 270

=> y x 5 + 90 = 270

=> y x 5 = 270 - 90

=> y x 5 = 180

=> y = 180 : 5

=> y = 36

Vậy...

năn nỉ đó ai nhanh nhát tick cho

\(\frac{9}{4}-y\times\frac{5}{6}=\frac{1}{2}+\frac{2}{3}\)

\(\frac{9}{4}-y\times\frac{5}{6}=\frac{7}{6}\)

           \(y\times\frac{5}{6}=\frac{9}{4}-\frac{7}{6}\)

           \(y\times\frac{5}{6}=\frac{13}{12}\)

                      \(y=\frac{13}{12}:\frac{5}{6}\)

                      \(y=\frac{13}{10}\)

9/4 - y × 5/6 = 1/2 + 1/3

9/4 - y × 5/6 = 5/6

         y × 5/6 = 9/4 - 5/6

         y × 5/6 = 17/12

         y           = 17/12 : 5/6

         y           = 17/10

la 17/10 do

mình ra 13/10 cơ mình thi vio rồi đúng 100% luôn đó nha

a) \(\left(3x-5\right)\left(5-3x\right)+9\left(x+1\right)^2=30\)

\(\Rightarrow15x-9x^2-25+15x+9\left(x^2+2x+1\right)-30=0\)

\(\Rightarrow30x-9x^2-25+9x^2+18x+9-30=0\)

\(\Rightarrow48x-46=0\)

\(\Rightarrow x=\frac{23}{24}\)

b) \(\left(x+4\right)^2-\left(x+1\right)\left(x-1\right)=16\)

\(\Rightarrow\left(x^2+8x+16\right)-\left(x^2-1\right)=16\)

\(\Rightarrow x^2+8x+16-x^2+1=16\)

\(\Rightarrow8x+17=16\)

\(\Rightarrow8x=-1\)

\(\Rightarrow x=\frac{-1}{8}\)

c) \(\left(y-2\right)^3-\left(y-3\right)\left(y^2+3y+9\right)+6\left(y+1\right)^2=49\)

\(\Rightarrow\left(y-2\right)^3-\left(y^3-3^3\right)+6\left(y^2+2y+1\right)=49\)

\(\Rightarrow y^3-6y^2+12y-8-y^3+27+6y^2+12y+6=49\)

\(\Rightarrow\left(y^3-y^3\right)+\left(-6y^2+6y^2\right)+\left(12y+12y\right)+\left(-8+27+6\right)=49\)

\(\Rightarrow24y+25=49\)

\(\Rightarrow24y=24\)

\(\Rightarrow y=1\)

d) \(\left(y+3\right)^3-\left(y+1\right)^3=56\)

\(\Rightarrow\left(y+3-y-1\right)[\left(y+3\right)^2+\left(y+3\right)\left(y+1\right)+\left(y+1\right)^2]=56\)

\(\Rightarrow2\left(y^2+6y+9+y^2+4y+3+y^2+2y+1\right)=56\)

\(\Rightarrow3y^2+12y+13=28\)

\(\Rightarrow\left(3y^2+15y\right)-\left(3y+15\right)=0\)

\(\Rightarrow3y\left(y+5\right)-3\left(y+5\right)=0\)

\(\Rightarrow3\left(y-1\right)\left(y+5\right)=0\)

\(\Rightarrow\orbr{\begin{cases}x-1=0\\x+5=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=1\\x=-5\end{cases}}\)