Bài 7 trang 43 Toán 6 Tập 2 | Cánh diều Giải Toán lớp 6

Bài 7 trang 43 Toán 6 Tập 2: Tính:

a) $\frac{17}{8}:\left(\frac{27}{8}+\frac{-11}{2}\right)$;

b) $\frac{28}{15}.\frac{1}{4^2}.3+\left(\frac{8}{15}-\frac{69}{60}.\frac{5}{23}\right):\frac{51}{54}$.

Lời giải

a) $\frac{17}{8}:\left(\frac{27}{8}+\frac{-11}{2}\right)$

$=\frac{17}{8}:\left(\frac{27}{8}+\frac{-44}{8}\right)$

$=\frac{17}{8}:\left(\frac{-17}{8}\right)$

$=\frac{17}{8}.\frac{8}{-17}$

= -1.

b) $\frac{28}{15}.\frac{1}{4^2}.3+\left(\frac{8}{15}-\frac{69}{60}.\frac{5}{23}\right):\frac{-51}{54}$

$=\frac{28}{15}.\frac{1}{16}.3+\left(\frac{8}{15}-\frac{69.5}{60.23}\right):\frac{-51}{54}$

$=\frac{28}{15}.\frac{1}{16}.3+\left(\frac{8}{15}-\frac{1}{4}\right).\frac{54}{-51}$

$=\frac{\mathrm{28.1.3}}{15.16}+\left(\frac{32}{60}-\frac{15}{60}\right).\frac{54}{-51}$

$=\frac{7}{20}+\frac{17}{60}.\frac{54}{-51}$

$=\frac{7}{20}+\frac{-18}{60}$

$=\frac{21}{60}+\frac{-18}{60}$

$=\frac{21-18}{60}$

$=\frac{3}{20}.$