( 2x - 1 )² = 25 . 9
( 7x - 11 )³ = 1000
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Những câu hỏi liên quan
NL
Nguyễn Lê Phước Thịnh
CTVHS
4 tháng 2 2021
Câu 1:
a) Ta có: 7x+21=0
\(\Leftrightarrow7x=-21\)
hay x=-3
Vậy: S={-3}
b) Ta có: 3x-2=2x-3
\(\Leftrightarrow3x-2-2x+3=0\)
\(\Leftrightarrow x+1=0\)
hay x=-1
Vậy: S={-1}
c) Ta có: 5x-2x-24=0
\(\Leftrightarrow3x=24\)
hay x=8
Vậy: S={8}
Câu 2:
a) Ta có: \(\left(2x+1\right)\left(x-1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}2x+1=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=-1\\x=1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=1\end{matrix}\right.\)
Vậy: \(S=\left\{-\dfrac{1}{2};1\right\}\)
b) Ta có: \(\left(2x-3\right)\left(-x+7\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-3=0\\-x+7=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}2x=3\\-x=-7\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{2}\\x=7\end{matrix}\right.\)
Vậy: \(S=\left\{\dfrac{3}{2};7\right\}\)
c) Ta có: \(\left(x+3\right)^3-9\left(x+3\right)=0\)
\(\Leftrightarrow\left(x+3\right)\left[\left(x+3\right)^2-9\right]=0\)
\(\Leftrightarrow\left(x+3\right)\left(x+3-3\right)\left(x+3+3\right)=0\)
\(\Leftrightarrow x\left(x+3\right)\left(x+6\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+3=0\\x+6=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-3\\x=-6\end{matrix}\right.\)
Vậy: S={0;-3;-6}
PK
1
12 tháng 4 2020
-(7x+11)⋮ 2x+4
⇒(7x+11)⋮ 2x+4 ⇒ 2(7x+11)⋮ 2x+4
7(2x+4) đương nhiên ⋮ 2x+4
⇒7(2x+4) - 2(7x+11) ⋮ 2x+4
Hay 6 ⋮ 2x+4
Ta có bảng sau:
| 2x+4 | 2 | 6 | -2 | -6 |
| x | -1 | 1 | -3 | 3 |
CT
0
CT
1
DT
Đỗ Thanh Hải
CTVVIP
16 tháng 10 2021
1 would you have done
2 rains
3 wouldn't have married
4 would have to
5 had known
6 will never pass
7 would catch
8 would have had
9 would have got
10 tries
11 had lost
12 wouldn't have gone
13 doesn't he come
14 wouldn't have come
15 had been
16 isn't
17 is
18 had been
19 fell
20 could help
21 had come - would have met
22 would buy - had
23 bought - wouldn't look
24 had known - would have met
25 wouldn't have gone - had asked
NV
4
VN
Võ Ngọc Phương
VIP
18 tháng 12 2023
\(7x-2x=6^{20}:36^9+44:11\)
\(=>x\left(7-2\right)=6^{20}:6^{18}+4\)
\(=>x5=6^2+4=36+4=40\)
\(=>x=40:5\)
\(=>x=8\)
LV
18 tháng 1 2022
một đòn bẫy dài một mét .đặt ở đâu để có thể dùng 3600n có thể nâng tảng đá nặng 120kg?
Câu 1:
(2\(x-1\))\(^2\) = 25.9
(2\(x\) - 1) = (5.3)\(^2\)
\(\left[\begin{array}{l}2x-1=-3.5\\ 2x-1=5.3\end{array}\right.\)
\(\left[\begin{array}{l}2x=-15+1\\ 2x=15+1\end{array}\right.\)
\(\left[\begin{array}{l}2x=-15+1\\ 2x=16\end{array}\right.\)
\(\left[\begin{array}{l}2x=-14\\ x=16:2\end{array}\right.\)
\(\left[\begin{array}{l}x=-7\\ x=8\end{array}\right.\)
Vậy \(x\in\left\lbrace-7;8\right\rbrace\)
Câu 2: (7\(x-11\))\(^3\) = 1000
(7\(x\) - 11)\(^3\) = 10\(^3\)
7\(x\) - 11 = 10
7\(x\) = 10 + 11
7\(x\) = 21
\(x=21:7\)
\(x=3\)
Vậy \(x=3\)