Đáp án:
3,a, $\frac{-143}{90}$
b, $\frac{-1}{4}$
4, a, $\frac{-49}{40}$
b, $\frac{32}{\sqrt[]{6}}$
Giải thích các bước giải:
Bài 3.
a, (0,3 + $\frac{4}{5}$).$\frac{1}{2}$ - $\frac{3}{4}$ + $\frac{1}{2}$.($\frac{2}{9}$ - 3)
= ($\frac{3}{10}$ + $\frac{4}{5}$).$\frac{1}{2}$ - $\frac{3}{4}$ + $\frac{1}{2}$.($\frac{2}{9}$ - $\frac{27}{9}$)
= $\frac{11}{10}$.$\frac{1}{2}$ - $\frac{3}{4}$ + $\frac{1}{2}$.$\frac{-25}{9}$
= $\frac{11}{20}$ - $\frac{3}{4}$ - $\frac{25}{18}$
= $\frac{99}{180}$ - $\frac{135}{180}$ - $\frac{250}{180}$
= $\frac{99-135-250}{180}$
= $\frac{-286}{180}$ = $\frac{-143}{90}$
b, (0,016).$\sqrt[]{\frac{1}{16}}$.$(-5)^3$.$\sqrt[]{\frac{1}{4}}$
= $\frac{2}{5^3}$.$\frac{1}{4}$.$(-5)^3$.$\frac{1}{2}$
= $\frac{-1}{4}$
Bài 4.
a, (0,4 + $\frac{3}{5}$).$\frac{5}{8}$ - $\frac{3}{4}$ + $\frac{1}{2}$.($\frac{4}{5}$ - 3)
= ($\frac{2}{5}$ + $\frac{3}{5}$).$\frac{5}{8}$ - $\frac{3}{4}$ + $\frac{1}{2}$.($\frac{4}{5}$ - $\frac{15}{5}$)
= $\frac{5}{8}$ - $\frac{3}{4}$ + $\frac{1}{2}$.$\frac{-11}{5}$
= $\frac{25}{40}$ - $\frac{30}{40}$ - $\frac{44}{40}$
= $\frac{25-30-44}{40}$
= $\frac{-49}{40}$
b, (-1,25).$\sqrt[]{\frac{1}{25}}$.$(-4)^3$.$\frac{2}{\sqrt[]{6}}$
=$\frac{-5}{4}$.$\frac{1}{5}$.$(-4)^3$.$\frac{2}{\sqrt[]{6}}$
= 16.$\frac{2}{\sqrt[]{6}}$
= $\frac{32}{\sqrt[]{6}}$
