Tính nhanh nếu có thể.

Đáp án+Giải thích các bước giải:

a) $\frac{3}{8}$ + $\frac{15}{-25}$ + $\frac{3}{5}$

= $\frac{3}{8}$ + -$\frac{3}{5}$ + $\frac{3}{5}$ 

= $\frac{3}{8}$ + (-$\frac{3}{5}$ + $\frac{3}{5}$) 

= $\frac{3}{8}$ + 0

= $\frac{3}{8}$

b) ($\frac{-7}{4}$ . $\frac{3}{8}$ + $\frac{-7}{4}$ . $\frac{5}{8}$) + $\frac{7}{15}$ : $\frac{-14}{5}$ 

= [$\frac{-7}{4}$ . ($\frac{3}{8}$ + $\frac{5}{8}$)] + $\frac{7}{15}$ : $\frac{-14}{5}$ 

= [$\frac{-7}{4}$ . 1) + $\frac{7}{15}$ : $\frac{-14}{5}$ 

= $\frac{-7}{4}$ + $\frac{7}{15}$ : $\frac{-14}{5}$ 

= $\frac{-7}{4}$ + $\frac{-1}{6}$ 

= $\frac{-23}{12}$  

c) 5 . |-$\frac{1}{2}$| + ($\frac{5}{9}$ - $\frac{7}{12}$) - $(\frac{2}{3}$ - $\frac{5}{6})^{2}$ 

= 5 . $\frac{1}{2}$ + ($\frac{5}{9}$ - $\frac{7}{12}$) - $(\frac{2}{3}$ - $\frac{5}{6})^{2}$ 

= $\frac{5}{2}$ + ($\frac{5}{9}$ - $\frac{7}{12}$) - $(\frac{2}{3}$ - $\frac{5}{6})^{2}$ 

= $\frac{5}{2}$ + $\frac{-1}{36}$ - $\frac{1}{36}$ 

= $\frac{89}{36}$ - $\frac{1}{36}$ 

= $\frac{22}{9}$