Question

Tìm x biết

A) x^2-25=0

B ) (2x-3)^2 - (2x-1)^2=0

Answer 1

a/ \(x^2-25=0\)

\(\Leftrightarrow x^2=25\)

\(\Leftrightarrow\left[{}\begin{matrix}x^2=5^2\\x^2=\left(-5\right)^2\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=-5\end{matrix}\right.\)

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b/ \(\left(2x-3\right)^2-\left(2x-1\right)^2=0\)

\(\Leftrightarrow\left(2x-3\right)^2=\left(2x-1\right)^2\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-3=2x-1\\2x-3=-2x+1\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-2x=3-1\\2x+2x=1+3\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}0x=2\left(loại\right)\\4x=4\end{matrix}\right.\)

\(\Leftrightarrow x=1\)

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