Question

Giai phuong trinh

|2x+1| = |5x+1|

Answer 1

\(\left|2x+1\right|=\left|5x+1\right|\)

\(\Leftrightarrow\left[{}\begin{matrix}2x+1=5x+1\\-2x-1=5x+1\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}-3x=0\\-7x=2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-\dfrac{2}{7}\end{matrix}\right.\)

Vậy S = {0, -2/7}

Answer 2

Vì 2 vế có gía tri k âm, nên bình phương 2 vế ta đc:

\((2x+1)^{2} \)=\((5x+1)^{2}\)

<=>\(4x^{2}\)+4x+1=\(25x^{2} \)+10x+1

<=>\(16x^{2}\)+6x=0

<=>2x(8x+3)=0

<=>x=0 hoăc x= -3/8

Vây.....

Answer 3

=>5x+1=2x+1 hoặc 5x+1=-2x-1

=>x=0 hoặc x=-2/7