Question

Tính hợp lí 

C =\(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{14}+1\frac{5}{7}\)

Answer 1

\(C=\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{14}+1\frac{5}{7}\)

\(C=\frac{5}{7}.\left(\frac{-2}{11}+\frac{-9}{14}+1\right)+1\)

\(C=\frac{5}{7}.\frac{27}{154}+1\)

\(C=\frac{135}{1078}+1\)

\(C=1\frac{135}{1078}\)

CHÚC BN HỌC TỐT!

Answer 2

ta có:

c=-5/7.2/11+-5/5.9/14+1/5/7

c=-10/77+-9/14+1/5/7

c=-79/154=1/5/7

c=185/154

Answer 3

\(C=\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{14}+1\frac{5}{7}\)

\(\Leftrightarrow C=\frac{-5}{7}\left(\frac{2}{11}+\frac{9}{14}\right)+\frac{12}{7}\)

\(\Leftrightarrow C=\frac{-5}{7}.\frac{127}{154}+\frac{12.154}{7.154}\)

\(\Leftrightarrow C=\frac{-5.127+12.154}{7.154}\)

\(\Leftrightarrow C=\frac{-635+1848}{1078}\)

\(\Leftrightarrow C=\frac{1213}{1078}\)