Đáp án+Giải thích các bước giải:
k,2$\frac{3}{4}$+$\frac{4}{21}$+$\frac{1}{4}$-$\frac{1}{2}$+$\frac{17}{21}$
=$\frac{11}{4}$+$\frac{4}{21}$+$\frac{1}{4}$-$\frac{1}{2}$+$\frac{17}{21}$
=($\frac{11}{4}$+$\frac{1}{4}$)+($\frac{4}{21}$+$\frac{17}{21}$)-$\frac{1}{2}$
=3+1-$\frac{1}{2}$
=4-$\frac{1}{2}$
=$\frac{7}{2}$
l,43$\frac{1}{4}$×$\frac{-2}{3}$-13$\frac{1}{4}$×$\frac{-2}{3}$
=(43$\frac{1}{4}$-13$\frac{1}{4}$)×$\frac{-2}{3}$
=30×$\frac{-2}{3}$
=-20
i,$\frac{3}{7}$×$\frac{58}{5}$-$\frac{3}{7}$×$\frac{53}{5}$
=$\frac{3}{7}$×($\frac{58}{5}$-$\frac{53}{5}$)
=$\frac{3}{7}$×1
=$\frac{3}{7}$
e,$7^{8}$×$(1/7)^{8}$
=$7^{8}$×$1^{8}$/$7^{8}$
=$1^{8}$
=1
