Đáp án:
a) $\dfrac{2}{3}$ + $\dfrac{4}{5}$ = $\dfrac{10}{15}$ + $\dfrac{12}{15}$ = $\dfrac{22}{15}$
b) $\dfrac{-2}{13}$ + $\dfrac{-11}{26}$ = $\dfrac{-4}{26}$ - $\dfrac{11}{26}$ = $\dfrac{-15}{26}$
c) $\dfrac{1}{2}$ - $\dfrac{5}{7}$ = $\dfrac{7}{14}$ - $\dfrac{10}{14}$ = $\dfrac{-3}{14}$
Tìm $x$
a) $x$ + $\dfrac{1}{2}$ = $\dfrac{3}{4}$
$x$ = $\dfrac{3}{4}$ - $\dfrac{1}{2}$
$x$ = $\dfrac{3 - 2}{4}$
$x$ = $\dfrac{1}{4}$
b) $x$ + $\dfrac{2}{3}$ = $\dfrac{3}{5}$
$x$ = $\dfrac{3}{5}$ - $\dfrac{2}{3}$
$x$ =$\dfrac{9 - 10}{15}$
$x$ = $\dfrac{-1}{15}$
Tính
$\dfrac{-1}{15}$ + $\dfrac{-1}{5}$ = $\dfrac{-1}{15}$ - $\dfrac{3}{15}$ = $\dfrac{-4}{15}$
#Ling
