Question

[ID Mini World: 71156040]

giúp tôi đi

Answer 1

[Yen Nhi]

Answer:

\(y^2-25-\left(y+5\right)=0\)

\(\Rightarrow y^2-5^2-\left(y+5\right)=0\)

\(\Rightarrow\left(y-5\right).\left(y+5\right)-\left(y+5\right)=0\)

\(\Rightarrow\left(y+5\right).[\left(y-5\right)-1]=0\)

\(\Rightarrow\left(y+5\right).\left(y-6\right)=0\)

\(\Rightarrow\orbr{\begin{cases}y+5=0\\y-6=0\end{cases}}\Rightarrow\orbr{\begin{cases}y=5\\y=-6\end{cases}}\)

\(y^4-2y^3+10y^2-20y=0\)

\(\Rightarrow\left(y^4-2y^3\right)+\left(10y^2-20y\right)=0\)

\(\Rightarrow y^3.\left(y-2\right).\left(y^3+10y\right)=0\)

\(\Rightarrow y.\left(y-2\right).\left(y^2+10\right)=0\)

Trường hợp 1: \(y=0\)

Trường hợp 2: \(y-2=0\Rightarrow y=2\)

Trường hợp 3: \(y^2+10=0\Rightarrow y^2=-10\) (Loại)