Tìm x biết
a,|x+5|=100
b,100 – | 25-x | = 40
c,|2x+1| = | 23-x |
d,|11-7x| – | 4x + 3|=0
Tìm x biết a,|x+5|=100 b,100 – | 25-x | = 40 c,|2x+1| = | 23-x | d,|11-7x| – | 4x + 3|=0
By Amara
By Amara
Tìm x biết
a,|x+5|=100
b,100 – | 25-x | = 40
c,|2x+1| = | 23-x |
d,|11-7x| – | 4x + 3|=0
a) | x+5 | = 100
=> x + 5 = 100 hoặc -100
+) Nếu x + 5 = 100
x = 100 – 5
x = 95
+) Nếu x + 5 = -100
x = -100 – 5
x = -105
b) 100 – | 25 – x | = 40
| 25 – x | = 100 – 40
| 25 – x | = 60
=> 25 – x = 60 hoặc -60
+) Nếu 25 – x = 60
x = 25 – 60
x = -35
+) Nếu 25 – x = -60
x = 25 – ( -60 )
x = 85
c) + d) mik ko bt làm 🙁
a. |x+5|=100
⇒ [x+5=100x+5=−100[x+5=100x+5=−100
⇒ [x=100−5x=−100−5[x=100−5x=−100−5
⇒ [x=95x=−105[x=95x=−105
b. 100-| 25-x | = 40
⇒ | 25-x | =100-40
⇒ | 25-x | =60
⇒ [25−x=6025−x=−60[25−x=6025−x=−60
⇒ [x=25−60x=25−(−60)[x=25−60x=25−(−60)
⇒ [x=−35x=85[x=−35x=85
c. |2x+1| = | 23-x |
⇒ [2x+1=23−x2x+1=−(23−x)[2x+1=23−x2x+1=−(23−x)
⇒ [2x+x=23−12x+1=−23+x[2x+x=23−12x+1=−23+x
⇒ [3x=222x−x=−23−1[3x=222x−x=−23−1
⇒ [x=223x=−24[x=223x=−24
d. |11-7x| – | 4x + 3|=0
⇒ |11−7x|=|4x+3||11−7x|=|4x+3|
⇒ [11−7x=4x+311−7x=−(4x+3)[11−7x=4x+311−7x=−(4x+3)
⇒ [7x−4x=3−1111−7x=−4x−3[7x−4x=3−1111−7x=−4x−3
⇒ [3x=−84x−7x=−3−11[3x=−84x−7x=−3−11
⇒ [x=−83−3x=−14[x=−83−3x=−14
⇒ [x=−83x=143[x=−83x=143