Question

Mn giúp mik với ạ

Tìm x:

(2x+5)^2-(x-3)^2=0

 

Answer 1

`(2x+5)^{2}-(x-3)^{2}=0`

`<=>[(2x+5)+(x-3)].[(2x+5)-(x-3)]=0`

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

`=>3x+2=0` hoặc `x+8=0`

`<=>x=-2/3` hoặc `x=-8`

Vậy `S={-2/3;-8}`

Answer 2

\(\left(2x+5-x+3\right)\left(2x+5+x-3\right)=0\\ \left(x+8\right)\left(3x+2\right)=0\\ \left[{}\begin{matrix}x+8=0\\3x+2=0\end{matrix}\right.=>\left[{}\begin{matrix}x=-8\\x=-\dfrac{2}{3}\end{matrix}\right.\)