37/7 . 13 + 51/13 . 22 + 85/22 . 37 + 68/37 . 49
= 17/3 . [1/7 - 1/13 + 1/13 - 1/22 + 1/22 - 1/37 + 1/37 - 1/49]
= 17/3 . [1/7 + (- 1/13 + 1/13 - 1/22 + 1/22 - 1/37 + 1/37) - 1/49]
= 17/3 . [1/7 - 1/49]
= 17/3 . 6/49
= 34/49
(7x−11)3=25.52+200
(7x−11)3=32.25+200
(7x−11)3=800+200=1000
(7x−11)3=1037
7x−11=10
7x=21
x=21:7
x=3.
3n+2⋮d3n+3⋮d{3n+2⋮d3n+3⋮d
⇒⇒ {3n+2⋮dn+1⋮d{3n+2⋮dn+1⋮d
⇒1⋮d⇒1⋮d
⇒d∈Ư(1)={±1}⇒d∈Ư(1)={±1}
⇒ƯCLN(3n+2;n+1)=±1⇒ƯCLN(3n+2;n+1)=±1
⇒A=⇒A= 3n+2n+13n+2n+1 là phân số tối giản