Toán Lớp 6: a) x . (x-9) = 0 b) (x-1) . (x+2) . (2x-4) = 0 c) 24 : (3x-2) = -3 d) -45 : 5 . (-3 -2x) = 3 giúp em với ạ

Question

Toán Lớp 6:  a) x . (x-9) = 0 b) (x-1) . (x+2) . (2x-4) = 0  c) 24 : (3x-2) = -3 d) -45 : 5 . (-3 -2x) = 3 giúp em với ạ

thienthanh · Answer

a) x ( x - 9 ) = 0     &hArr;  ( left[  begin{array}{l}x=0  x-9=0 end{array}  right. )      &hArr;  ( left[  begin{array}{l}x=0  x=9 end{array}  right. )      Vậy x = 0 ; x = 9     b) ( x - 1 ) . ( x + 2 ) . ( 2x - 4 ) = 0     &hArr;  ( left[  begin{array}{l}x-1=0  x+2=0  2x-4=0 end{array}  right. )      &hArr;  ( left[  begin{array}{l}x=1  x=-2  2x=4 end{array}  right. )      &hArr;  ( left[  begin{array}{l}x=1  x=-2  x=2 end{array}  right. )      Vậy x = 1 ; x = - 2 ; x = 2     c) 24 : ( 3x - 2 ) = - 3     &hArr; ( 3x - 2 ) = 24 : ( - 3 )     &hArr; 3x - 2 = - 8     &hArr; 3x = - 8 + 2     &hArr; 3x = - 6     &hArr; x = - 2     Vậy x = - 2     d) - 45 : 5 . ( - 3 - 2x ) = 3     &hArr; - 9 . ( - 3 - 2x ) = 3     &hArr; - 9 . ( - 3 ) . ( - 9 ) . ( - 2x ) = 3     &hArr; 27 + 18x = 3     &hArr; 18x = 3 - 27     &hArr; 18x = - 24     &hArr; x = - 24 : 18     &hArr; x = - 4/3     Vậy x = - 4/3

trucoanh55 · Answer

a) x . ( x - 9 ) = 0   &rArr; x = 0 hoặc x = 0 + 9 = 9   Vậy x = 9   b) ( x - 1 ) . ( x + 2 ) . ( 2x - 4 ) = 0   &rArr; x - 1 = 0 hoặc x + 2 = 0 hoặc 2x - 4 = 0   &rArr; x = 0 + 1 hoặc x = 0 - 2 hoặc 2 . x = 0 + 4   &rArr; x = 1 hoặc x = - 2 hoặc x = 4 : 2 = 2   $ text{Vậy x &isin; { 1; - 2; 2 }}$   c) 24 : ( 3x - 2 ) = - 3   3x - 2 = 24 : ( - 3 )   3 . x = - 8 + 2   x = - 6 : 3   x = - 2   Vậy x = - 2   d) - 45 : 5 . ( - 3 - 2x ) = 3   - 3 - 2 . x = 3 : ( - 9 )   - 2 . x = - 1/3 + 3   x = 8/3 : ( - 2 )   x = - 4/3   Vậy x = - 4/3