Question

[mytrang tran]

 

Bài 1: thực hiện phép tính (tính hợp lý nếu có thể)

 a) -15/8 .( 8/-15 + 32/ 27) - 15/7

 b) 41,54 + 23,17 + 8,46 - 3,17

 c) 3.( 32,1 - 6,32 ) + 7.32,1 + 3.0,32

Answer 1

[Nguyễn Lê Phước Thịnh]

a: \(-\dfrac{15}{8}\left(\dfrac{8}{-15}+\dfrac{32}{27}\right)-\dfrac{15}{7}\)

\(=\dfrac{15}{8}\cdot\dfrac{8}{15}-\dfrac{15}{8}\cdot\dfrac{32}{27}-\dfrac{15}{7}\)

\(=1-\dfrac{15}{7}-\dfrac{15}{27}\cdot\dfrac{32}{8}\)

\(=\dfrac{-8}{7}-4\cdot\dfrac{5}{9}=\dfrac{-8}{7}-\dfrac{20}{9}\)

\(=-\dfrac{72}{63}-\dfrac{140}{63}=-\dfrac{212}{63}\)

b: \(41,54+23,17+8,46-3,17\)

=(41,54+8,46)+(23,17-3,17)

=50+20

=70

c: \(3\cdot\left(32,1-6,32\right)+7\cdot32,1+3\cdot0,32\)

\(=3\cdot32,1-3\cdot6,32+7\cdot32,1+3\cdot0,32\)

\(=32,1\left(3+7\right)-3\left(6,32-0,32\right)\)

\(=321-3\cdot6=321-18=303\)

Answer 2

[Nguyễn Thị Thương Hoài]

a; - \(\dfrac{15}{8}\).(\(\dfrac{8}{-15}\) + \(\dfrac{32}{27}\)) - \(\dfrac{15}{7}\)

= - \(\dfrac{15}{18}\).(\(\dfrac{8}{-15}\)) - \(\dfrac{15}{8}\).(\(\dfrac{32}{27}\)) - \(\dfrac{15}{7}\)

= 1 - \(\dfrac{20}{9}\) - \(\dfrac{15}{7}\)

= \(\dfrac{-11}{9}\) - \(\dfrac{15}{7}\)

= - \(\dfrac{212}{63}\)