Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
1. a, 3x + |x - 2| = 8
<=> |x - 2| = 8 - 3x
Xét 2 TH :
TH1: x - 2 = 8 - 3x
<=> x + 3x = 8 + 2
<=> 4x = 10
<=> x = \(\dfrac{5}{2}\) (thỏa mãn)
TH2: x - 2 = -(8 - 3x)
<=> x - 2 = -8 + 3x
<=> -2 + 8 = 3x - x
<=> 6 = 2x
<=> x = 3 (thỏa mãn)
b, 5 - |x - 1| = 4
<=> |x - 1| = 1
<=> \(\left[{}\begin{matrix}x-1=1\\x-1=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=0\end{matrix}\right.\) (thỏa mãn)
@Nguyễn Hoàng Vũ
2. 5.(x - 2) - 4.(1 - 3x) = |3 - 7| + 2.(1 + 2x)
<=> 5x - 10 - 4 + 12x = 4 + 2 + 4x
<=> 17x - 14 = 6 + 4x
<=> 17x - 4x = 6 + 14
<=> 13x = 20
<=> x = \(\dfrac{20}{13}\) (thỏa mãn)
@Nguyễn Hoàng Vũ
>> Với toán lớp 6 chắc đề bài là tìm x,y nhỉ ? . Lần sau bạn nhớ viết tên đề bài nhé ;) <<
a) \((x−3).(y−2)=7\)
\(\Rightarrow\left(x\text{−}3\right)\inƯ\left(7\right)\)
\(\Rightarrow x\text{−}3\in\left\{1;\text{−}1;7;\text{−}7\right\}\)
Ta có bảng sau :
| \(x\text{−}3\) | \(1\) | \(−1\) | \(7\) | \(−7\) |
| \(x\) | \(4\) | \(2 \) | \(10\) | \(\text{−}4\) |
| \(y−2\) | 7 | −7 | 1 | −1 |
| \(y\) | 9 | −5 | 3 | 1 |
Vậy .....
b) \((x−1).(y−1)=2\)
\(\Rightarrow\left(x\text{−}1\right)\inƯ\left(2\right)\)
\(\Rightarrow x\text{−}1\in\left\{1;\text{−}1;2;\text{−}2\right\}\)
Ta có bảng sau :
| x−1 | 1 | −1 | 2 | −2 |
| x | 2 | 0 | 3 | −1 |
| y−1 | 2 | −2 | 1 | −1 |
| y | 3 | −1 | 2 | 0 |
Vậy ......
c) \((x−1).(y−2) = 2\)
\(\Rightarrow x\text{−}1\inƯ\left(2\right)\)
\(\Rightarrow x\text{−}1\in\left\{1;\text{−}1;2;\text{−}2\right\}\)
Ta có bảng sau :
| x−1 | 1 | −1 | 2 | −2 |
| x | 2 | 0 | 3 | −1 |
| y−2 | 2 | −2 | 1 | −1 |
| y | 4 | 0 | 3 | 1 |
Vậy ...
Bài 1:
\(\left(-\dfrac{72}{40}-\dfrac{144}{60}-2\dfrac{1}{3}\right):\left(\dfrac{45}{100}-\dfrac{25}{60}+-\dfrac{75}{25}\right)\)
\(=\left(-\dfrac{9}{5}-\dfrac{12}{5}-\dfrac{7}{3}\right):\left(\dfrac{9}{20}-\dfrac{5}{12}+-3\right)\)
\(=\left(-\dfrac{27}{15}-\dfrac{36}{15}-\dfrac{21}{15}\right):\left(\dfrac{27}{60}-\dfrac{25}{60}+-3\right)\)
\(=\left(-\dfrac{28}{5}\right):\left(-\dfrac{89}{30}\right)\)
\(=\left(-\dfrac{28}{5}\right).\left(-\dfrac{30}{89}\right)\)
\(=\dfrac{168}{89}\)
a/\(5x\cdot\left(x-\frac{1}{3}\right)=0\)
Chia làm 2 TH :
TH 1: \(5x=0\Rightarrow x=0\)
TH 2:\(x-\frac{1}{3}=0\Rightarrow x=\frac{1}{3}\)
\(\Rightarrow x\in\left\{0;\frac{1}{3}\right\}\)
b/\(\left(x+\frac{1}{4}\right)\cdot\left(x-\frac{3}{7}\right)=0\)
Chia làm 2 Th
Th1 : \(x+\frac{1}{4}=0\Rightarrow x=-\frac{1}{4}\)
Th2 :\(x-\frac{3}{7}=0\Rightarrow x=\frac{3}{7}\)
\(\Rightarrow x\in\left\{-\frac{1}{4};\frac{3}{7}\right\}\)
1) \(5x\left(x-\frac{1}{3}\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}5x=0\\x-\frac{1}{3}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=0\\x=\frac{1}{3}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=0\\x=\frac{1}{3}\end{cases}}\)
2) \(\left(x+\frac{1}{4}\right)\left(x-\frac{3}{7}\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}x+\frac{1}{4}=0\\x-\frac{3}{7}=0\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-\frac{1}{4}\\x=\frac{3}{7}\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=-\frac{1}{4}\\x=\frac{3}{7}\end{cases}}\)
Ta có:
\(\left(\right. \frac{13 \frac{2}{9} - 15 \frac{2}{3}}{18 \frac{3}{7} - 17 \frac{1}{4}} \cdot \frac{30^{2} - 5^{4}}{25 - 12 \cdot 5^{2}} \left.\right) \cdot x = \frac{\frac{2}{11} + \frac{3}{13} + \frac{4}{15} + \frac{5}{17}}{4 \frac{1}{11} + \frac{5}{13} + \frac{9}{15} + \frac{13}{17}}\)
Bước 1: Đổi hỗn số về phân số
- \(13 \frac{2}{9} = \frac{119}{9}\),
- \(15 \frac{2}{3} = \frac{47}{3}\),
- \(18 \frac{3}{7} = \frac{129}{7}\),
- \(17 \frac{1}{4} = \frac{69}{4}\)
Bước 2: Tính toán từng phần
Ta có:
\(\frac{119}{9} - \frac{47}{3} = \frac{119 - 141}{9} = \frac{- 22}{9}\) \(\frac{129}{7} - \frac{69}{4} = \frac{516 - 483}{28} = \frac{33}{28}\) \(30^{2} - 5^{4} = 900 - 625 = 275\) \(25 - 12 \cdot 25 = 25 - 300 = - 275\)
Khi đó:
\(\left(\right. \frac{- 22}{9} \div \frac{33}{28} \cdot \frac{275}{- 275} \left.\right) = \left(\right. \frac{- 22}{9} \cdot \frac{28}{33} \cdot \left(\right. - 1 \left.\right) \left.\right) = \frac{616}{297}\)
Bước 3: Tính vế phải
Tử số:
\(\frac{2}{11} + \frac{3}{13} + \frac{4}{15} + \frac{5}{17} = \frac{35494}{36465}\)
Mẫu số:
\(4 \frac{1}{11} + \frac{5}{13} + \frac{9}{15} + \frac{13}{17} = \frac{149645}{36465}\)
→ Vế phải:
\(\frac{35494}{36465} \div \frac{149645}{36465} = \frac{35494}{149645}\)
Bước 4: Giải phương trình
\(\frac{616}{297} \cdot x = \frac{35494}{149645} \Rightarrow x = \frac{35494}{149645} \cdot \frac{297}{616} = \frac{813}{7118}\)
Vậy:
\(\boxed{x = \frac{813}{7118}}\)
hỉu không =]]]
4a) \(\frac{-2}{3}x=\frac{3}{10}-\frac{1}{5}=\frac{1}{10}\)
\(\Leftrightarrow x=\frac{1}{10}:\frac{-2}{3}=\frac{1}{10}.\frac{3}{-2}=\frac{3}{-20}\)
Vậy x=\(\frac{3}{-20}\)
b) \(\frac{2}{3}x-\frac{3}{2}x=\frac{5}{12}\)
\(\Leftrightarrow\left(\frac{2}{3}-\frac{3}{2}\right)x=\frac{5}{12}\)
\(\Leftrightarrow\frac{-5}{6}x=\frac{5}{12}\)
\(\Leftrightarrow x=\frac{5}{12}:\frac{-5}{6}=\frac{5}{12}.\frac{6}{-5}=\frac{1}{-2}\)
Vậy x=\(\frac{1}{-2}\)
g)Sửa đề: \(\left|4x-1\right|=\left(-3\right)^2\)
\(\Leftrightarrow\left|4x-1\right|=9\)
\(\Rightarrow\left[{}\begin{matrix}4x-1=9\\4x-1=\left(-9\right)\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{5}{2}\\x=-2\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{5}{2};-2\right\}\)
i) \(\left(x-1^3\right)=125\)
\(\Leftrightarrow x-1=125\)
\(\Leftrightarrow x=125+1=126\)
Vậy x=126
k) \(\left(x+\frac{1}{2}\right).\left(\frac{2}{3}-2x\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+\frac{1}{2}=0\\\frac{2}{3}-2x=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{-1}{2}\\x=\frac{1}{3}\end{matrix}\right.\)
Vậy \(x\in\left\{\frac{-1}{2};\frac{1}{3}\right\}\)
=> (7+x).(3+x2)=0
TH1:
7+x=0
x=0-7
x=-7
TH2: 3+x2=0
=>
\(x\in\)0Vậy x=-7