Câu 3: Trang 28 sách toán VNEN lớp 6 tập 2
Điền phân số thích hợp vào chỗ trống (...)
a) $\frac{1}{6}\;+\;(...) = \frac{-2}{3}$.
b) $\frac{-2}{3}\;+\;(...) = \frac{3}{5}$.
c) $\frac{1}{6}\;-\;(...) = \frac{3}{24}$.
d) $\frac{-7}{19}\;-\;(...) = 0$.
Bài Làm:
a) $\frac{1}{6}\;+\;(...) = \frac{-2}{3}$.
$\Rightarrow (...) = \frac{-2}{3}\;-\;\frac{1}{6}$.
$\Rightarrow (...) = \frac{-4}{6}\;-\;\frac{1}{6}$.
$\Rightarrow (...) = \frac{-4\;-\;1}{6}$.
$\Rightarrow (...) = \frac{-5}{6}$
b) $\frac{-2}{3}\;+\;(...) = \frac{3}{5}$.
$\Rightarrow (...) = \frac{3}{5}\;-\;\frac{-2}{3}$.
$\Rightarrow (...) = \frac{9}{15}\;+\;\frac{10}{15}$.
$\Rightarrow (...) = \frac{9\;+\;10}{15}$.
$\Rightarrow (...) = \frac{19}{15}$
c) $\frac{1}{6}\;-\;(...) = \frac{3}{24}$.
$\Rightarrow (...) = \frac{3}{24}\;-\;\frac{1}{6}$.
$\Rightarrow (...) = \frac{3}{24}\;-\;\frac{4}{24}$.
$\Rightarrow (...) = \frac{3\;-\;4}{24}$.
$\Rightarrow (...) = \frac{-1}{24}$
d) $\frac{-7}{19}\;-\;(...) = 0$.
$\Rightarrow (...) = \frac{-7}{9}\;-\;0$.
$\Rightarrow (...) =\frac{-7}{9}$.