Toán (2x-1)(x+7)=x^2 -49 đáp án đúng sẽ cho 5 sao 18/07/2021 By Bella (2x-1)(x+7)=x^2 -49 đáp án đúng sẽ cho 5 sao
`(2x-1)(x+7)=x^2 -49` `⇔(2x-1)(x+7)=(x-7)(x+7)` `⇔(2x-1)(x+7)-(x-7)(x+7)=0` `⇔(x+7)(2x-1-x+7)=0` `⇔(x+7)(x+6)=0` `⇔`\(\left[ \begin{array}{l}x+7=0\\x+6=0\end{array} \right.\) `⇔`\(\left[ \begin{array}{l}x=-7\\x=-6\end{array} \right.\) $\color{black}{\huge\text{xin hay nhất }}$ Trả lời
`(2x-1)(x+7)=x^2 – 49` `<=> (2x – 1 ) (x+7)=(x-7)(x+7)` `<=> (2x – 1 ) (x+7) -(x-7)(x+7) =0 ` `<=>(x+7)(2x-1-x+7)=0` `<=>(x+7)(x+6)=0` `<=>`\(\left[ \begin{array}{l}x+7=0\\x+6=0\end{array} \right.\) `<=>`\(\left[ \begin{array}{l}x=-7\\x=-6\end{array} \right.\) Vậy `S = { -6,-7}` Trả lời
`(2x-1)(x+7)=x^2 -49`
`⇔(2x-1)(x+7)=(x-7)(x+7)`
`⇔(2x-1)(x+7)-(x-7)(x+7)=0`
`⇔(x+7)(2x-1-x+7)=0`
`⇔(x+7)(x+6)=0`
`⇔`\(\left[ \begin{array}{l}x+7=0\\x+6=0\end{array} \right.\)
`⇔`\(\left[ \begin{array}{l}x=-7\\x=-6\end{array} \right.\)
$\color{black}{\huge\text{xin hay nhất }}$
`(2x-1)(x+7)=x^2 – 49`
`<=> (2x – 1 ) (x+7)=(x-7)(x+7)`
`<=> (2x – 1 ) (x+7) -(x-7)(x+7) =0 `
`<=>(x+7)(2x-1-x+7)=0`
`<=>(x+7)(x+6)=0`
`<=>`\(\left[ \begin{array}{l}x+7=0\\x+6=0\end{array} \right.\)
`<=>`\(\left[ \begin{array}{l}x=-7\\x=-6\end{array} \right.\)
Vậy `S = { -6,-7}`