Toán Lớp 7: A)2x-1=6 b)3/4x-1/2-3/7 c)5-[3x-1]=3. Thank giup help

Question

Toán Lớp 7:  A)2x-1=6    b)3/4x-1/2-3/7  c)5-[3x-1]=3. Thank giup help

lanngocha · Answer

A)2x-1=6 $ Longrightarrow$ 2x = 6 + 1 $ Longrightarrow$ 2x =7 $ Longrightarrow$ x = 7 : 2 $ Longrightarrow$ x = 3,5 $ Longrightarrow$ x kh&ocirc;ng l&agrave; số n&agrave;o Vậy x kh&ocirc;ng l&agrave; số n&agrave;o   b)3/4x-1/2-3/7  $ Longrightarrow$ đề lỗi  c)5-[3x-1]=3  $ Longrightarrow$ 3x-1 = 5 - 3 $ Longrightarrow$ 3x-1 = 2 $ Longrightarrow$ 3x = 2 + 1 $ Longrightarrow$ 3x = 3 $ Longrightarrow$ x = 3 : 3 $ Longrightarrow$ x = 1 Vậy x = 1

daithanh · Answer

$ text{2x - 1 = 6}$   $ text{&rArr;2x = 7}$   $ text{&rArr;x = }$ $ dfrac{7}{2}$   Vậy $ text{x = }$ $ dfrac{7}{2}$   _________________________________   $ dfrac{3}{4}$$ text{x -}$ $ dfrac{1}{2}$ = $ dfrac{3}{7}$   &rArr;$ dfrac{3}{4}$$ text{x}$ = $ dfrac{13}{14}$   &rArr;$ text{x = $ dfrac{26}{21}$ }$   Vậy $ text{x = $ dfrac{26}{21}$ }$   _________________________________   $ text{5 - ( 3x - 1 ) = 3 }$   $ text{&rArr;3x - 1 = 2}$   $ text{&rArr;3x = 3}$   $ text{&rArr;x = 1}$   Vậy $ text{x = 1}$