B.1.Rút gọn các phân số sau : a)19.7-19/38 ; b) 3^2.16/2^3.15 . B.2 Tìm x. a) x-3/-x=-7/6 b) 5/6=x+1/x 09/10/2021 Bởi Isabelle B.1.Rút gọn các phân số sau : a)19.7-19/38 ; b) 3^2.16/2^3.15 . B.2 Tìm x. a) x-3/-x=-7/6 b) 5/6=x+1/x
a) ${\dfrac{19.7-19}{38}=\dfrac{19.(7-1)}{19.2}=\dfrac{19.6}{19.2}=\dfrac{6}{2}=3}$ b) ${\dfrac{3^2.16}{2^3.15}=\dfrac{3.3.8.2}{8.3.5}=\dfrac{3.2}{5}=\dfrac{6}{5}}$ 2) a) ${\dfrac{x-3}{-x}=\dfrac{-7}{6}}$ `=> 6.(x-3)=-7.(-x)``=> 6x-18 =7x``=> 7x-6x=-18``=> x=-18` b) ${\dfrac{5}{6}=\dfrac{x+1}{x}}$ `=> 6.(x+1)=5x``=> 6x+6 =5x``=> 6x-5x=6``=> x=6` Bình luận
trong hinh nha
a) ${\dfrac{19.7-19}{38}=\dfrac{19.(7-1)}{19.2}=\dfrac{19.6}{19.2}=\dfrac{6}{2}=3}$
b) ${\dfrac{3^2.16}{2^3.15}=\dfrac{3.3.8.2}{8.3.5}=\dfrac{3.2}{5}=\dfrac{6}{5}}$
2)
a) ${\dfrac{x-3}{-x}=\dfrac{-7}{6}}$
`=> 6.(x-3)=-7.(-x)`
`=> 6x-18 =7x`
`=> 7x-6x=-18`
`=> x=-18`
b) ${\dfrac{5}{6}=\dfrac{x+1}{x}}$
`=> 6.(x+1)=5x`
`=> 6x+6 =5x`
`=> 6x-5x=6`
`=> x=6`