B1:
e.\(-5\dfrac{1}{7}+3\dfrac{2}{5}\)
\(=\dfrac{17}{5}-\dfrac{36}{7}\)
\(=\dfrac{119}{35}-\dfrac{180}{35}\)
\(=-\dfrac{61}{35}\)
f.\(-2\dfrac{1}{3}-1\dfrac{2}{7}\)
\(=-\left(\dfrac{7}{3}+\dfrac{9}{7}\right)\)
\(-\left(\dfrac{49}{21}+\dfrac{27}{21}\right)\)
\(=-\dfrac{76}{21}\)
B2:
a.\(\dfrac{3}{4}.x=1\)
\(x=1:\dfrac{3}{4}\)
\(x=\dfrac{4}{3}\)
b.\(\dfrac{4}{7}.x=\dfrac{9}{8}-0,125\)
\(\dfrac{4}{7}.x=\dfrac{9}{8}-\dfrac{1}{8}\)
\(\dfrac{4}{7}.x=1\)
\(x=1:\dfrac{4}{7}\)
\(x=\dfrac{7}{4}\)
Bài 1:
e) \(-5\dfrac{1}{7}+3\dfrac{2}{5}=-\dfrac{36}{7}+\dfrac{17}{5}=-\dfrac{180}{35}+\dfrac{119}{35}=-\dfrac{61}{35}\)
f) \(-2\dfrac{1}{3}-1\dfrac{2}{7}=-\dfrac{7}{3}-\dfrac{9}{7}=-\dfrac{49}{21}-\dfrac{27}{21}=-\dfrac{76}{21}\)
Bài 2:
a) \(\dfrac{3}{4}x=1\Rightarrow x=1:\dfrac{3}{4}\Rightarrow x=\dfrac{4}{3}\)
b) \(\dfrac{4}{7}x=\dfrac{9}{8}-0,125\)
\(\dfrac{4}{7}x=\dfrac{9}{8}-\dfrac{1}{8}\)
\(\dfrac{4}{7}x=\dfrac{8}{8}=1\)
\(x=1:\dfrac{4}{7}\)
\(x=\dfrac{7}{4}\)
ai đúng ạ ??? 2 kết quả e vs f khác nhau
