Question

Giúp mình 2 câu này với mình đang cần gấp

Tìm x

a) 2x² - 16x = 0

b) (2x - 1)² - 25 = 0

 

Answer 1

a) \(2x^2-16x=0\)

\(\Rightarrow2x\left(x-8\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\x=8\end{matrix}\right.\)

b) \(\left(2x-1\right)^2-25=0\)

\(\Rightarrow\left(2x-1-5\right)\left(2x-1+5\right)=0\)

\(\Rightarrow4\left(x-3\right)\left(x+2\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)

Answer 2

\(b.\left(2x-1\right)^2-25=0\)

<=>\(\left(2x-1-5\right)\left(2x-1+5\right)=0\)

<=>\(\left[{}\begin{matrix}2x=6\\2x=-4\end{matrix}\right.< =>\left[{}\begin{matrix}x=3\\x=-2\end{matrix}\right.\)

\(a.2x^2-16x=0< =>2x\left(x-8\right)=0\)

\(< =>\left[{}\begin{matrix}2x=0\\x-8=0\end{matrix}\right.< =>\left[{}\begin{matrix}x=0\\x=8\end{matrix}\right.\)