Bài 6.21 trang 11 SBT Toán 6 Kết nối tri thức với cuộc sống: Điền số thích hợp vào bảng sau...

a

$\dfrac{1}{5}$

$\dfrac{12}{17}$

$\dfrac{3}{4}$

$\dfrac{-7}{30}$

$\dfrac{2}{3}$

b

$\dfrac{4}{5}$

$\dfrac{-21}{17}$

$\dfrac{5}{12}$

$\dfrac{8}{45}$

$\dfrac{5}{4}$

a+b

a-b

a

$\dfrac{1}{5}$

$\dfrac{12}{17}$

$\dfrac{3}{4}$

$\dfrac{-7}{30}$

$\dfrac{2}{3}$

b

$\dfrac{4}{5}$

$\dfrac{-21}{17}$

$\dfrac{5}{12}$

$\dfrac{8}{45}$

$\dfrac{5}{4}$

a+b

1

$\dfrac{-9}{17}$

$\dfrac{7}{6}$

$\dfrac{-1}{18}$

$\dfrac{23}{12}$

a-b

$\dfrac{-3}{5}$

$\dfrac{33}{17}$

$\dfrac{1}{3}$

$\dfrac{-37}{90}$

$\dfrac{-7}{12}$