Toán Tìm x : a,|x + 2|+|x – 1|=4 b, 2 . |x – 3|- 7=1/7 31/07/2021 By Faith Tìm x : a,|x + 2|+|x – 1|=4 b, 2 . |x – 3|- 7=1/7
a) TH1 : X+ 2 + X -1 =4 2X +( 2- 1 ) = 4 2X + 1 = 4 2X = 4 -1 2X = 3 X = 3:2 X = 1,5 TH2 X+2 + X-1 = -4 2X + ( 2-1 ) = -4 2X + 1 = -4 2X = -4 -1 2X = 5 X = 5:2 X = 2,5 B ) 2. | X-3 | – 7 = 1/7 2 .| X-3 | = 1/7 – 7 2. | X- 3 | =-48 / 7 | X- 3 | = -48/ 7 :2 | X – 3 | = -24 / 7 TH1 : X-3 = -24/7 X = -24/7 + 3 X= -24/7 + 21/7 X= -3 / 7 TH2 X-3 = 24/7 X = 24/7 +3 X= 24/7 + 21/7 X = 45 /7 CHÚC BẠN HỌC TỐT CHO MK XIN CÂU TRẢ LỜI HAY NHẤT AK Trả lời
Giải thích các bước giải: a/ $|x+2|+|x-1|=4$ $⇒ |x+2|=4-|x-1|$ $⇒ \left[ \begin{array}{l}x+2=4-x+1\\x+2=4+x-1\end{array} \right.$ $⇒ \left[ \begin{array}{l}x=\dfrac{3}{2}\\2=3 \text{(luôn sai)}\end{array} \right.$ $⇒ x=\dfrac{3}{2}$ b/ $2.|x-3|-7=\dfrac{1}{7}$ $⇒ 2.|x-3|=\dfrac{1}{7}+7=\dfrac{50}{7}$ $⇒ |x-3|=\dfrac{50}{7}.\dfrac{1}{2}=\dfrac{25}{7}$ $⇒ \left[ \begin{array}{l}x-3=\dfrac{25}{7}\\x-3=-\dfrac{25}{7}\end{array} \right.$ $⇒ \left[ \begin{array}{l}x=\dfrac{46}{7}\\x=-\dfrac{4}{7}\end{array} \right.$ Chúc bạn học tốt !!! Trả lời
a) TH1 : X+ 2 + X -1 =4
2X +( 2- 1 ) = 4
2X + 1 = 4
2X = 4 -1
2X = 3
X = 3:2
X = 1,5
TH2
X+2 + X-1 = -4
2X + ( 2-1 ) = -4
2X + 1 = -4
2X = -4 -1
2X = 5
X = 5:2
X = 2,5
B ) 2. | X-3 | – 7 = 1/7
2 .| X-3 | = 1/7 – 7
2. | X- 3 | =-48 / 7
| X- 3 | = -48/ 7 :2
| X – 3 | = -24 / 7
TH1 :
X-3 = -24/7
X = -24/7 + 3
X= -24/7 + 21/7
X= -3 / 7
TH2
X-3 = 24/7
X = 24/7 +3
X= 24/7 + 21/7
X = 45 /7
CHÚC BẠN HỌC TỐT
CHO MK XIN CÂU TRẢ LỜI HAY NHẤT AK
Giải thích các bước giải:
a/ $|x+2|+|x-1|=4$
$⇒ |x+2|=4-|x-1|$
$⇒ \left[ \begin{array}{l}x+2=4-x+1\\x+2=4+x-1\end{array} \right.$
$⇒ \left[ \begin{array}{l}x=\dfrac{3}{2}\\2=3 \text{(luôn sai)}\end{array} \right.$
$⇒ x=\dfrac{3}{2}$
b/ $2.|x-3|-7=\dfrac{1}{7}$
$⇒ 2.|x-3|=\dfrac{1}{7}+7=\dfrac{50}{7}$
$⇒ |x-3|=\dfrac{50}{7}.\dfrac{1}{2}=\dfrac{25}{7}$
$⇒ \left[ \begin{array}{l}x-3=\dfrac{25}{7}\\x-3=-\dfrac{25}{7}\end{array} \right.$
$⇒ \left[ \begin{array}{l}x=\dfrac{46}{7}\\x=-\dfrac{4}{7}\end{array} \right.$
Chúc bạn học tốt !!!