- Tính giá trị của biểu thức:
\(A=\frac{-5x}{21}+\frac{-5y}{21}+\frac{-5z}{21}\)
biết x + y = -z
2. Tìm x biết:
- \(\left(x-5\right)\cdot\frac{30}{100}=\frac{200x}{100}+5\)
- \(60\%x+0,4x+\frac{x}{3}=2\)
- \(1\frac{2}{5}+\left(\frac{\frac{2}{7}+\frac{2}{17}+\frac{2}{37}}{\frac{5}{7}+\frac{5}{17}+\frac{5}{37}}\right)\cdot x=\frac{16}{5}\)
1.
A=\(\frac{-5x+-5y+-5z}{21}=\frac{-5\left(x+y+z\right)}{21}=\frac{-5}{21}.x+y+z\)
A= -z+z=0
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