Tìm x biết: a)2/3x+ 5/7=3/10; b)-21/13x+1/3=2/3

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Bài 2: Tìm x, biết:

a) \( \frac{2}{3} + \frac{5}{7} = \frac{3}{10} \)

b) \( \frac{21}{13} x + \frac{1}{3} = \frac{2}{3} \)

c) \( \frac{3}{7} \cdot \frac{1}{7} \cdot x = \frac{3}{14} \)

d) \( -\frac{1}{3} \left( \frac{1}{7} - x \right) = -\frac{1}{21} \)

e) \( \left( x - \frac{1}{2} \right)^2 = 0 \)

f) \( (2x - 1)^3 = \frac{1}{8} \)

g) \( \left( \frac{1}{2} - \frac{2}{3} \right)^2 = \left( \frac{1}{2} x - \frac{2}{3} \right)^4 \)