a) 15/34+7/21+19/34-20/15+3/7 b) 26 và 1/5.3/4-3/4.44 và 1/5
2 câu trả lời
Đáp án:
a) 3/7
Giải thích các bước giải: \[\begin{array}{l}a)\frac{{15}}{{34}} + \frac{7}{{21}} + \frac{{19}}{{34}} - \frac{{20}}{{15}} + \frac{3}{7}\\ = \left( {\frac{{15}}{{34}} + \frac{{19}}{{34}}} \right) + \left( {\frac{7}{{21}} + \frac{3}{7}} \right) - \frac{{20}}{{15}}\\ = \,\,\,\,\,\,\,\,\,\,1\,\,\,\,\,\,\,\,\,\,\,\,\,\, + \,\,\,\left( {\frac{1}{3} + \frac{3}{7}} \right) - \frac{4}{3}\\ = \,\,\,\,\,\,\,\,\,\,1\,\,\,\,\,\,\,\,\,\,\,\,\,\, + \left( {\frac{1}{3} - \frac{4}{3}} \right) + \frac{3}{7}\\ = \,\,\,\,\,\,\,\,\,\,1\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, + \left( { - 1} \right)\,\,\,\,\,\,\,\,\, + \frac{3}{7}\\ = \frac{3}{7}\end{array}\]
