Question

Tìm x biết

(3x-1)²=(x+5)²

Answer 1

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

\(\Rightarrow\) 3x-x = 5+1

2x = 6

\(\Rightarrow\) x=3

Answer 2

Th1:

3x - 1 = x + 5

<=> 3x - 1 = x + 5

<=> 3x - x = 1 + 5

<=> 2x = 6

<=> x = 3

TH2:

1 - 3x = x + 5

<=> 3x + x = 1 - 5

<=> 4x = -4

<=> x = -1

Vậy phương trình có nhiệm x = 3 và x = -1

Answer 3

( 3x - 1 )² = ( x + 5 )²

⇔ ( 3x - 1 )² - ( x + 5 )² = 0

⇔ ( 3x - 1 - x - 5 )( 3x - 1 + x +5 ) = 0

⇔( 2x - 6 )( 4x + 4 ) = 0

\(\Leftrightarrow\left\{{}\begin{matrix}2x-6=0\\4x+4=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2x=6\\4x=-4\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{6}{2}\\x=-\dfrac{4}{4}\end{matrix}\right.\)

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

Vậy x = 3 hoặc x = -1