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SV
8
SS
10 tháng 2 2018
a. -3
b. -71
c. -40
d. 358
e. ?i
f. 10
mình chỉ cho đáp án được thôi vì mình đang gấp nên ko thể trình bày được, câu e mình ko hiểu bạn ghi gì hết. bạn gửi lại câu e đi.
10 tháng 2 2018
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PT
1
OC
1 tháng 10 2017
a) 5 . 2^2x - 29.2^3 = 11.2^3
5 . 2^2x - 29 . 8 = 11 . 8
5 . 2^2x - 232 = 88
5 . 2^2x = 88 + 232
5 . 2^2x = 320
2^2x = 320 : 5
2 ^ 2 x = 64
2 ^ 2 x = 2 ^ 6 ( cùng cơ số )
\(\Rightarrow\) x = 6 : 2
x = 3
b)5.x^12 - 40x ^ 9 = 0
5 . x^12 = 40 . x^9
5 . x^12 = 8 . 5 . x^9
5 . x^12 = 5 . (x^9 . 8)
x^12 = x^9 .8
x^12 = x^9 . x^3= x^9 . 8
x^3 = 8
X^3 = 2^3 ( cùng cơ số )
\(\Rightarrow\)x = 2
NL
1
NT
Nguyễn Thị Thương Hoài
Giáo viên
VIP
27 tháng 8 2023
a, \(x\) + (\(x\) + 1) + (\(x\) + 3) = 153
\(x\) + \(x\) + 1 + \(x\) + 3 = 153
3\(x\) + 4 = 153
3\(x\) = 153 - 4
3\(x\) = 149
\(x\) = 149 : 3
\(x\) = \(\dfrac{149}{3}\)
b, (\(2x-7\)) - (\(x\) + 135) =0
2\(x\) - 7 - \(x\) - 135 = 0
\(x\) - 142 = 0
\(x\) = 142
SL
3
18 tháng 9 2016
a ) 2x - 1 = 7
2x = 7 + 1
2x = 8
x = 8 : 2
x = 4
b ) 3 ( x + 5 ) = 21
( x + 5 ) = 21 : 3
( x + 5 ) = 7
x = 2
c ) 20 - ( 3x - 1 ) = 15
( 3x - 1 ) = 20 - 15
( 3x - 1 ) = 5
3x = 6
x = 2
d ) ( x - 135 ) -120 = 0
( x - 135 ) = 120
x = 120 + 135
x = 255
18 tháng 9 2016
a)2x - 1 = 7
=>2x=8
=>x=4
b) 3(x+5) = 21
=>x+5=7
=>x=2
c) 20 - (3x - 1) = 15
=>3x-1=5
=>3x=6
=>x=2
d) (x - 135) - 120 = 0
=>x-135=120
=>x=155
Q
7 tháng 1 2018
a/ \(2n+12⋮n+2\)
Mà \(n+2⋮n+2\)
\(\Leftrightarrow\hept{\begin{cases}2n+12⋮n+2\\2n+4⋮n+2\end{cases}}\)
\(\Leftrightarrow8⋮n+2\)
\(\Leftrightarrow n+2\inƯ\left(8\right)\)
Suy ra :
+) n + 2 = 1 => n = -1 (loại)
+) n + 2 = 2 => n = 0
+) n + 2 = 4 => n = 2
+) n + 2 = 8 => n = 6
Vậy ......
b/ \(3n+5⋮n-2\)
Mà \(n-2⋮n-2\)
\(\Leftrightarrow\hept{\begin{cases}3n+5⋮n-2\\3n-6⋮n-2\end{cases}}\)
\(\Leftrightarrow11⋮n+2\)
\(\Leftrightarrow n+2\inƯ\left(11\right)\)
\(\Leftrightarrow\orbr{\begin{cases}n+2=1\\n+2=11\end{cases}}\) \(\Leftrightarrow\orbr{\begin{cases}n=-1\left(loại\right)\\n=9\end{cases}}\)
Vậy ..
Q
7 tháng 1 2018
a/ \(\left(x+3\right)\left(x^2+1\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+3=0\\x^2+1=0\end{cases}}\) \(\Leftrightarrow\orbr{\begin{cases}x=-3\\x^2=-1\left(loại\right)\end{cases}}\)
Vậy ....
b/ \(\left(x+7\right)\left(x^2-36\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+7=0\\x^2-36=0\end{cases}}\) \(\Leftrightarrow\orbr{\begin{cases}x=-7\\x^2=36\end{cases}}\) \(\Leftrightarrow\orbr{\begin{cases}x=-7\\x=6or=-6\end{cases}}\)
Vậy ...
NT
0
24 tháng 1 2016
câu d : ( x - 2 ) . ( x + 4 ) = 0
=) x - 2 =0 hay x + 4 = 0
- x - 2 = 0
x = 0 + 2
x = 2
- x + 4 = 0
x = 0 - 4
x = - 4
Vậy x = 2 ; x = -4
19 tháng 4 2017
a)10-Ix+1I=5
Ix+1I=10-5
Ix+1I=5=>x+1=+-5
TH1:x+1=5 TH2:x+1=-5
=>x=4 =>x=-6
b)(2.x+7)+135=0
2.x+7=0-135
2.x+7=-135
2.x=-135-7
2.x=-142
x=-142:2
x=-71
c)1/2x-2/5=1/5
1/2x=1/5+2/5
1/2x=3/5
x=3/5:1/2
x=6/5
d)1/2x+150%x=2014
1/2x+15/10x=2014
x.(1/2+15/10)=2014
x.2=2014
x=2014:2
x=1007
mình trả lời cho cậu rồi nhớ nha
(2x-7)-(x+135)=0
=>2x-7=x+135
2x-x=7+135
x=142