a.
\(5x^3+5=0\)
\(5x^3=-5\)
\(x^3=-1\)
\(x^3=\left(-1\right)^3\)
\(\Rightarrow x=-1\)
b.
\(2\left(x+5\right)-x^2-5x=0\)
\(2x+10-x^2-5x=0\)
\(-x^2-3x+10=0\)
\(-x^2+5x-2x+10=0\)
\(-x\left(x-5\right)-2\left(x-5\right)=0\)
\(\left(x-5\right)\left(-x-2\right)=0\)
\(\orbr{\begin{cases}x-5=0\\-x-2=0\end{cases}}\)
\(\orbr{\begin{cases}x=5\\-x=2\end{cases}}\)
\(\orbr{\begin{cases}x=5\\x=-2\end{cases}}\)
5x3 + 5 = 0
<=> 5( x3 + 1 ) = 0
<=> x3 + 1 = 0
<=> x3 = -1
<=> x3 = (-1)3
<=> x = -1
2( x + 5 ) - x2 - 5x = 0
<=> 2( x + 5 ) - ( x2 + 5x ) = 0
<=> 2( x + 5 ) - x( x + 5 ) = 0
<=> ( x + 5 )( 2 - x ) = 0
<=> \(\orbr{\begin{cases}x+5=0\\2-x=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-5\\x=2\end{cases}}\)
Câm B mk bị nhầm xíu
\(-x^2-3x+10=0\)
\(-x^2+2x-5x+10=0\)
\(-x\left(x-2\right)-5\left(x-2\right)=0\)
\(\left(x-2\right)\left(-x-5\right)=0\)
\(\orbr{\begin{cases}x-2=0\\-x-5=0\end{cases}}\)
\(\orbr{\begin{cases}x=2\\x=-5\end{cases}}\)
a) \(5x^3+5=0\)
\(\Leftrightarrow x^3+1=0\)
\(\Leftrightarrow x^3=-1\)
\(\Rightarrow x=-1\)
b) \(2\left(x+5\right)-x^2-5x=0\)
\(\Leftrightarrow2\left(x+5\right)-x\left(x+5\right)=0\)
\(\Leftrightarrow\left(2-x\right)\left(x+5\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x=2\\x=-5\end{cases}}\)
