Question

mọi người giải giúp mình với

Answer 1

1. 3x(x - 7) + 2x - 14 = 0

<=> 3x(x - 7) + 2(x - 7) = 0

<=> (3x + 2)(x - 7) = 0

<=> \(\left[{}\begin{matrix}3x+2=0\\x-7=0\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}x=-\dfrac{2}{3}\\x=7\end{matrix}\right.\)

2. x³ + 3x² - (x + 3) = 0

<=> x²(x + 3) - (x + 3) = 0

<=> (x² - 1)(x + 3) = 0

<=> (x - 1)(x + 1)(x + 3) = 0

<=> \(\left[{}\begin{matrix}x-1=0\\x+1=0\\x+3=0\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}x=1\\x=-1\\x=-3\end{matrix}\right.\)

3. 15x - 5 + 6x² - 2x = 0

<=> 5(3x - 1) + 2x(3x - 1) = 0

<=> (5 + 2x)(3x - 1) = 0

<=> \(\left[{}\begin{matrix}5+2x=0\\3x-1=0\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}x=\dfrac{-5}{2}\\x=\dfrac{1}{3}\end{matrix}\right.\)

4. 5x - 2 - 25x² + 10x = 0

<=> (5x - 2) - (25x² - 10x) = 0

<=> (5x - 2) - 5x(5x - 2) = 0

<=> (1 - 5x)(5x - 2) = 0

<=> \(\left[{}\begin{matrix}1-5x=0\\5x-2=0\end{matrix}\right.\)

<=> \(\left[{}\begin{matrix}x=\dfrac{1}{5}\\x=\dfrac{2}{5}\end{matrix}\right.\)