Giải các pt sau; a) 2x ( x – 5 ) – 4 ( 5 – x ) = 0. b)| x – 3 |= – 3x + 17. 02/09/2021 Bởi Skylar Giải các pt sau; a) 2x ( x – 5 ) – 4 ( 5 – x ) = 0. b)| x – 3 |= – 3x + 17.
$a.2x(x-5)-4(5-x)=0$ $⇔2x(x-5)+4(x-5)=0$ $⇔(x-5)(2x+4)=0$ ⇔\(\left[ \begin{array}{l}x-5=0\\2x+4=0\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=5\\x=-2\end{array} \right.\) Vậy \(\left[ \begin{array}{l}x=5\\x=-2\end{array} \right.\) $b.|x-3|=-3x+17$ ⇔\(\left[ \begin{array}{l}x-3=-3x+17\\x-3=3x-17\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x+3x=17+3\\x-3x=-17+3\end{array} \right.\) ⇔\(\left[ \begin{array}{l}4x=20\\-2x=-14\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=5\\x=7\end{array} \right.\) Vậy \(\left[ \begin{array}{l}x=5\\x=7\end{array} \right.\) Bình luận
a) 2x(x-5)-4(5-x)=0 ⇒ 2x(x-5)+4(x-5)=0 ⇒ (2x+4).(x-5)=0 ⇒ 2x+4=0⇒2x=-4⇒x=-2 x-5=0⇒x=5 b) |x-3|=-3x+17 ⇒ x-3=-3x+17 ⇒ x-3=3x-17 ⇒ x+3x=17+3 ⇒ x-3x=-17+3 ⇒ 4x=20 ⇒ -2x=-14 ⇒ x=5 ⇒ x=7 Bình luận
$a.2x(x-5)-4(5-x)=0$
$⇔2x(x-5)+4(x-5)=0$
$⇔(x-5)(2x+4)=0$
⇔\(\left[ \begin{array}{l}x-5=0\\2x+4=0\end{array} \right.\) ⇔\(\left[ \begin{array}{l}x=5\\x=-2\end{array} \right.\)
Vậy \(\left[ \begin{array}{l}x=5\\x=-2\end{array} \right.\)
$b.|x-3|=-3x+17$
⇔\(\left[ \begin{array}{l}x-3=-3x+17\\x-3=3x-17\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x+3x=17+3\\x-3x=-17+3\end{array} \right.\)
⇔\(\left[ \begin{array}{l}4x=20\\-2x=-14\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=5\\x=7\end{array} \right.\)
Vậy \(\left[ \begin{array}{l}x=5\\x=7\end{array} \right.\)
a) 2x(x-5)-4(5-x)=0
⇒ 2x(x-5)+4(x-5)=0
⇒ (2x+4).(x-5)=0
⇒ 2x+4=0⇒2x=-4⇒x=-2
x-5=0⇒x=5
b) |x-3|=-3x+17
⇒ x-3=-3x+17 ⇒ x-3=3x-17
⇒ x+3x=17+3 ⇒ x-3x=-17+3
⇒ 4x=20 ⇒ -2x=-14
⇒ x=5 ⇒ x=7