Bài 1 :
\(c,3y-\dfrac{11}{5}=\dfrac{12}{25}\\ 3y=\dfrac{12}{25}+\dfrac{11}{5}\\ 3y=\dfrac{12}{25}+\dfrac{55}{25}\\ 3y=\dfrac{67}{25}\\ \Rightarrow y=\dfrac{67}{75}\\ d,\dfrac{6}{13}+y=\dfrac{-7}{65}\\ y=\dfrac{-7}{65}-\dfrac{6}{13}\\ y=\dfrac{-91}{845}-\dfrac{390}{845}\\ \Rightarrow y=-\dfrac{481}{845}\)
2:
a: =26/8-5/8=21/8
b: =147/175+100/175=247/175
c: =80/24+52/24-42/24=90/24=15/4
d: =1-1/2+1/2-1/3+...+1/49-1/50=49/50
e: =1/2-1/3+1/3-1/4+...+1/2019-1/2020=2018/2020=1009/1010
Bài 1 :
\(a,y-\dfrac{12}{5}=\dfrac{1}{7}\\y=\dfrac{1}{7}+\dfrac{12}{5}\\ y=\dfrac{5}{35}+\dfrac{84}{35}\\ \Rightarrow y=\dfrac{89}{35}\\ b,\dfrac{-7}{8}-y=\dfrac{-3}{5}\\ y=\dfrac{-7}{8}-\dfrac{-3}{5}\\ y=\dfrac{-35}{40}-\dfrac{-24}{40}\\ \Rightarrow y=\dfrac{-11}{40}\)
