Bài 4 (1đ): Tính bằng cách thuận tiện nhất.
x + x - x
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TL:
\(\frac{3}{5}.\frac{4}{7}+\frac{3}{5}.\frac{9}{7}-\frac{3}{5}.\frac{3}{7}\)
\(=\frac{3}{5}.\left(\frac{4}{7}+\frac{9}{7}-\frac{3}{7}\right)\)
\(=\frac{3}{5}.\frac{10}{7}\)
\(=\frac{6}{7}\)
-HT-