Question

[Phương]

tìm x biết 

c) x( 2x - 3 ) - 2( 3 - 2x) =0

d) 25x² - 36 =0

Answer 1

[Lightning Farron]

c) x( 2x - 3 ) - 2( 3 - 2x) =0

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

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

\(\Leftrightarrow\left[\begin{array}{nghiempt}x+2=0\\2x-3=0\end{array}\right.\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}x=-2\\x=\frac{3}{2}\end{array}\right.\)

d) 25x² - 36 =0

\(\Leftrightarrow\left(5x\right)^2-6^2=0\)

\(\Leftrightarrow\left(5x-6\right)\left(5x+6\right)=0\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}5x-6=0\\5x+6=0\end{array}\right.\)

\(\Leftrightarrow x=\pm\frac{6}{5}\)

Answer 2

[Trần Việt Linh]

a) \(x\left(2x-3\right)-2\left(3-2x\right)=0\)

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

=>\(\left[\begin{array}{nghiempt}2x-3=0\\x+2=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=\frac{3}{2}\\x=-2\end{array}\right.\)

b) \(25x^2-36=0\)

\(\Leftrightarrow\left(5x-6\right)\left(5x+6\right)=0\)

\(\Leftrightarrow\left[\begin{array}{nghiempt}5x-6=0\\5x+6=0\end{array}\right.\)\(\Leftrightarrow\left[\begin{array}{nghiempt}x=\frac{6}{5}\\x=-\frac{6}{5}\end{array}\right.\)