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a: =>4x-5=0 hoặc 5/4x-2=0
=>x=5/4 hoặc x=2:5/4=2*4/5=8/5
b: =>(1/12+19/6-30,75)*x-8=102
=>-55/2x=110
=>x=-4
Ta làm vế kia trước:
\(\left(\frac{3}{5}+0,415+\frac{1}{200}\right):0,01=\left(\frac{3}{5}+\frac{83}{200}+\frac{1}{200}\right):0,01\)
\(=\left(\frac{120}{200}+\frac{83}{200}+\frac{1}{200}\right):0,01\)
\(=\frac{204}{200}:\frac{1}{100}=\frac{51}{50}.100=102\)
=> \(\left(\frac{1}{12}+\frac{19}{6}-30,75\right).x-8=102\)
\(\left(\frac{1}{12}+\frac{19}{6}-\frac{123}{4}\right).x=102+8=110\)
\(\left(\frac{1}{12}+\frac{38}{12}-\frac{369}{12}\right).x=110\)
\(-\frac{330}{12}.x=110\)
\(-\frac{55}{2}.x=110\)
\(x=110:-\frac{55}{2}=110.-\frac{2}{55}=-4\)
**** CHO MK NHA , TKS ^^
\(\left(\dfrac{1}{12}+\dfrac{19}{6}-\dfrac{123}{4}\right).x-8=\left(\dfrac{3}{5}+\dfrac{83}{200}+\dfrac{1
}{200}\right)\): \(\dfrac{1}{100}\)
\(\dfrac{-53}{2}\) . x - 8 = \(\dfrac{51}{50}\): \(\dfrac{1}{100}\)
\(\dfrac{-53}{2}.x-8=\)102
\(\dfrac{-53}{2}\).x = 102 + 8
\(\dfrac{-53}{2}\).x = 110
x = 110 : \(\dfrac{-53}{2}\)
x = \(\dfrac{-204}{53}\)
\(\left(\dfrac{1}{2}+\dfrac{19}{6}-30,75\right).x-8=\left(\dfrac{3}{5}+0,415+\dfrac{1}{200}\right):0.01\)
\(\left(\dfrac{1}{2}+\dfrac{19}{6}-\dfrac{123}{4}\right).x-8=\left(\dfrac{3}{5}+\dfrac{83}{200}+\dfrac{1}{200}\right):\dfrac{1}{100}\)
\(\dfrac{-325}{12}.x-8=\dfrac{51}{50}:\dfrac{1}{100}\)
\(\dfrac{-325}{12}.x-8=102\)
\(\dfrac{-325}{12}.x=102+8\)
\(\dfrac{-325}{12}.x=110\)
\(x=110:\dfrac{-325}{12}\)
\(x=\dfrac{-264}{65}\)
Mk thấy bài 1 và 2 dễ nên bạn tự làm nha
3
+)Ta có n-2 \(⋮\)n-2
=>2.(n-2)\(⋮\)n-2
=>2n-4\(⋮\)n-2(1)
+)Theo bài ta có:2n+1\(⋮\)n-2(2)
+)Từ (1) và (2)
=>(2n+1)-(2n-4)\(⋮\)n-2
=>2n+1-2n+4\(⋮\)n-2
=>5\(⋮\)n-2
=>n-2\(\in\)Ư(5)={\(\pm\)1;\(\pm\)5}
+)Ta có bảng:
| n-2 | -1 | 1 | -5 | 5 |
| n | 1\(\in\)Z | 3\(\in\)Z | -3\(\in\)Z | 7\(\in\)Z |
Vậy n\(\in\){1;3;-3;7}
Chúc bn học tốt
a. 5.(–8).( –2).(–3) b. 4.(–5)2 + 2.(–5) – 20
=(-5).8.(-2).(-3) ={(-5).2} {4+1}-20
=(-5)(-2)(-3).8 =(-10).5-20=-50-20=-70
=10.(-24)=-240
\((\dfrac{1}{12}+3\dfrac{1}{6}-30,75)x-8=\left(\dfrac{3}{5}+0,415+\dfrac{1}{200}\right):0,01\)
\(\dfrac{-55}{2}.x-8=\dfrac{51}{50}:0,01\)
\(\dfrac{-55}{2}.x-8=102\)
\(\dfrac{-55}{2}.x=110\)
\(x=-4\)
co may tinh ma ban
Vậy hộ mink mink k cho tại ngại ấn mà