Question

Giúp mình nha : 

Đề bài : Thực hiện các phép tính sau :

a) 8x5 + (-3)x9

b) 2/5 + 1/5 x ( -3/4 ) 

c) 2 : ( 1/2 - 2/3 ) 

Answer 1

\(a.8.5+\left(-3\right).9\)

\(=40+-27\)

\(=-13\)

Answer 2

\(a,8\times5+(-3)\times9=40+(-27)=13\)

\(b,\frac{2}{5}+\frac{1}{5}\times\left[\frac{-3}{4}\right]\)

\(=\frac{2}{5}+\frac{-3}{20}\)

\(=\frac{8}{20}+\frac{-3}{20}=\frac{5}{20}=\frac{1}{4}\)

\(c,2:\left[\frac{1}{2}-\frac{2}{3}\right]=2:\left[\frac{3}{6}-\frac{4}{6}\right]=2:\frac{-1}{6}=2\times\frac{6}{-1}=-12\)

Answer 3

\(b.\frac{2}{5}+\frac{1}{5}\times\frac{-3}{4}\)

\(=\frac{2}{5}+\frac{-3}{20}\)

\(=\frac{8}{20}+\frac{-3}{20}\)

\(=\frac{5}{20}\)

\(=\frac{1}{4}\)

Answer 4

\(c.2:\left(\frac{1}{2}-\frac{2}{3}\right)\)

\(=2:\left(\frac{3}{6}-\frac{4}{6}\right)\)

\(=2:\frac{-1}{6}\)

\(=\frac{12}{-1}\)

\(=\frac{-12}{1}=-12\)

Answer 5

cảm ơn mấy bạn nha .-.