Question

Tính hợp lí

a) 7/-25+ -18/25+ 4/23+ 5/7+ 19/23

b) 7/19 x 8/11 + 7/19 x 3/11+ 12/19

Nhanh lên, mk đg cần gấp

Answer 1

\(a,\dfrac{7}{-25}+\dfrac{-18}{25}+\dfrac{4}{23}+\dfrac{5}{7}+\dfrac{19}{23}\)

\(=\left(\dfrac{-7}{25}+\dfrac{-18}{25}\right)+\left(\dfrac{4}{23}+\dfrac{19}{23}\right)+\dfrac{5}{7}\)

\(=\left(-1\right)+1+\dfrac{5}{7}\)

\(=0+\dfrac{5}{7}=\dfrac{5}{7}\)

b, \(\dfrac{7}{19}.\dfrac{8}{11}+\dfrac{7}{19}.\dfrac{3}{11}+\dfrac{12}{19}\)

\(=\dfrac{7}{19}\left(\dfrac{8}{11}+\dfrac{3}{11}\right)+\dfrac{12}{19}\)

\(=\dfrac{7}{19}.1+\dfrac{12}{19}\)

\(=\dfrac{7}{19}+\dfrac{12}{19}=1\)

Answer 2

a. \(\dfrac{7}{-25}+\dfrac{-18}{25}+\dfrac{4}{23}+\dfrac{5}{7}+\dfrac{19}{23}\)

\(=\left(\dfrac{-7}{25}+\dfrac{-18}{25}\right)+\left(\dfrac{4}{23}+\dfrac{19}{23}\right)+\dfrac{5}{7}\)

\(=-1+1+\dfrac{5}{7}\)

\(=\dfrac{5}{7}\)

b. \(\dfrac{7}{19}\cdot\dfrac{8}{11}+\dfrac{7}{19}\cdot\dfrac{3}{11}+\dfrac{12}{19}\)

\(=\dfrac{7}{19}\left(\dfrac{8}{11}+\dfrac{3}{11}\right)+\dfrac{12}{19}\)

\(=\dfrac{7}{19}\cdot1+\dfrac{12}{19}\)

\(=\dfrac{7}{19}+\dfrac{12}{19}\)

\(=1\)

Answer 3

a. \(\dfrac{7}{-25}+\dfrac{-18}{25}+\dfrac{4}{23}+\dfrac{5}{7}+\dfrac{19}{23}\)

= \(\left(\dfrac{7}{-25}+\dfrac{-18}{25}\right)+\left(\dfrac{4}{23}+\dfrac{19}{23}\right)+\dfrac{5}{7}\)

= \(\left(-1\right)+1+\dfrac{5}{7}\)

= \(0+\dfrac{5}{7}=\dfrac{5}{7}\)

b. \(\dfrac{7}{19}.\dfrac{8}{11}+\dfrac{7}{19}.\dfrac{3}{11}+\dfrac{12}{19}\)

= \(\dfrac{7}{19}.\left(\dfrac{8}{11}+\dfrac{3}{11}\right)+\dfrac{12}{19}\)

= \(\dfrac{7}{19}.1+\dfrac{12}{19}\)

= \(\dfrac{7}{19}+\dfrac{12}{19}=1\)