Question

Giải phương trình

1. 4x^2 -1=(2x+1)(3x-5)

Answer 1

\(4x^2-1=\left(2x+1\right)\left(3x-5\right)\)

\(\Rightarrow\left(2x-1\right)\left(2x+1\right)=\left(2x+1\right)\left(3x-5\right)\)

\(\Rightarrow\left(2x-1\right)\left(2x+1\right)-\left(2x+1\right)\left(3x-5\right)=0\)

\(\Rightarrow\left(2x+1\right)\left(2x-1-3x+5\right)=0\)

\(\Rightarrow\left(2x+1\right)\left(4-x\right)=0\)

\(\Rightarrow\left[{}\begin{matrix}2x+1=0\\4-x=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=4\end{matrix}\right.\)

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