Đáp án+Giải thích các bước giải:
`1) x(x-5)(x+5)-(x-2)(x²+2x+4)=3`
`⇔x(x²-25)-(x³-8)=3`
`⇔x³-25x-x³+8=3`
`⇔-25x+8=3`
`⇔-25x=-5`
`⇔x=1/5`
Vậy `S={1/5}`
`2) 25x²-2=0`
`⇔(5x)²-(√2)²=0`
`⇔(5x-√2)(5x+√2)=0`
$⇔\left[\begin{matrix} 5x-√2=0\\ 5x+√2=0\end{matrix}\right.$
$⇔\left[\begin{matrix} 5x=√2\\ 5x=-√2\end{matrix}\right.$
$⇔\left[\begin{matrix} x=\frac{√2}{5}\\ x=-\frac{√2}{5}\end{matrix}\right.$
vậy `S={\frac{√2}{5};-\frac{√2}{5}}`
`3) (x+2)²=(2x-1)²`
`⇔(x+2)²-(2x-1)²=0`
`⇔[(x+2)-(2x-1)] [(x+2)+(2x-1)]=0`
`⇔(x+2-2x+1)(x+2+2x-1)=0`
`⇔(-x+3)(3x+1)=0`
$⇔\left[\begin{matrix} -x+3=0\\ 3x+1=0\end{matrix}\right.$
$⇔\left[\begin{matrix} x=3\\ x=-1/3\end{matrix}\right.$
Vậy `S={3; -1/3}`
Chúc bn hc tốt🥰
$\text{#LinhSad}$
