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a) \(\frac{3}{4}x-\frac{1}{4}=2\left(x-3\right)+\frac{1}{4}x\)
\(\frac{3}{4}x-\frac{1}{4}=2x-6+\frac{1}{4}x\)
\(\frac{3}{4}x-2x-\frac{1}{4}x=\frac{1}{4}-6\)
\(x\left(\frac{3}{4}-2-\frac{1}{4}\right)=-\frac{23}{4}\)
\(-\frac{3}{2}x=-\frac{23}{4}\)
\(x=-\frac{23}{4}\div\left(-\frac{3}{2}\right)\)
\(x=\frac{23}{6}\)
1a)1+2+3+...+x=0
\(\frac{x.\left(x+1\right)}{2}\)=0
x.(x+1) =0:2
x.(x+1) =0
x.(x+1) =0.1
vây x=0
tich dung cho minh nha
a) \(\left(2x-1\right)^2-25=0\)
\(\left(2x-1\right)^2=0+25=25\)
\(\left(2x-1\right)^2=5^2=\left(-5\right)^2\)
\(\Rightarrow\left[\begin{array}{nghiempt}2x-1=5\\2x-1=-5\end{array}\right.\Rightarrow\left[\begin{array}{nghiempt}2x=6\\2x=-4\end{array}\right.\Rightarrow\left[\begin{array}{nghiempt}x=3\\x=-2\end{array}\right.\)
b) \(8x^3-50x=0\)
\(2x\left(4x^2-25\right)=0\)
\(\Rightarrow\left[\begin{array}{nghiempt}2x=0\\4x^2-25=0\end{array}\right.\Rightarrow\left[\begin{array}{nghiempt}x=0\\4x^2=25\Rightarrow x^2=\frac{25}{4}\Rightarrow\left[\begin{array}{nghiempt}x=\frac{5}{2}\\x=-\frac{5}{2}\end{array}\right.\end{array}\right.\)
1. \(\frac{x-3}{x+2}=\frac{3}{4}\)
=> \(4(x-3)=3(x+2)\)
=> 4x - 12 = 3x + 6
=> 4x - 12 - 3x = 6
=> 4x - 3x - 12 = 6
=> x = 18
2. \(\frac{4-x}{x-1}=\frac{-5}{6}\)
=> 6[4 - x] = -5[x - 1]
=> 24 - 6x = 5 - 5x
=> 24 - 6x - 5 = 5x
=> 24 - 5 = 6x - 5x
=> 19 = x
=> x = 19
3. \(\frac{3-x}{-x+2}=\frac{-1}{3}\)
=> 3[3 - x] = -1[-x + 2]
=> 9 - 3x = x - 2
=> 9 - 3x + x = -2
=> 9 - 4x = -2
=> 4x = 9 - [ -2]
=> 4x = 9 + 2 = 11
=> x = 11/4
4. \(\frac{x-1}{12}=\frac{-3}{1-x}\)
=> [x-1][1-x] = -36
=> -[x-1]2 = -36
=> [x-1]2 = 36
=> [x-1]2 = 62
=> x -1 = 6 hoặc x - 1 = -6
=> x = 7 hoặc x = -5
5 . |x - 3 | - 8 = -4
=> |x - 3| = -4 + 8
=> |x - 3| = 4
=> x - 3 = 4 hoặc x - 3 = -4
=> x = 7 hoặc x = -1
Mấy bài sau tương tự