Toán Lớp 6: C.( 2x + 6 ) chia hết cho ( x+2 ) D.( 2x + 3 ) chia hết cho ( 3x + 2 )

Question

Toán Lớp 6:  C.( 2x + 6 ) chia hết cho ( x+2 ) D.( 2x + 3 ) chia hết cho ( 3x + 2 )

bichhhathu · Answer

c, 2x + 6  vdots x + 2   => 2x + 4 + 2  vdots x + 2   => 2(x + 2) + 2  vdots x + 2   V&igrave; 2(x + 2)  vdots x + 2 n&ecirc;n 2  vdots x + 2   => x + 2 &isin; Ư (2) = {1 ; - 1 ; 2 ; - 2}   => x &isin; {-1 ; - 3 ; 0 ; -4}   d, 2x + 3  vdots 3x + 2   => 3(2x + 3)  vdots 3x + 2   => 6x + 9  vdots 3x + 2   => 6x + 4 + 5  vdots 3x + 2   => 2(3x + 2) + 5  vdots 3x + 2   V&igrave; 2(3x + 2)  vdots 3x + 2 n&ecirc;n 5  vdots 3x + 2   => 3x + 2 &isin; Ư (5) = {1 ; - 1 ; 5 ;  - 5}   => 3x &isin; {-1 ; - 3 ; 3 ; - 7}   => x &isin; { frac{-1}{3} ; - 1 ; 1 ;  frac{-7}{3}}

huyenmi76 · Answer

c) 2x + 6  vdots x + 2   => 2x + 4 + 2  vdots x + 2   => 2(x+2) + 2 vdots x + 2   => 2(x+2)  vdots x + 2   => 2  vdots x + 2   => x + 2 &isin; Ư(2) = {&plusmn;1;&plusmn;2}   => x &isin; {-1;-3;0;-4}   Vậy x &isin; {-1;-3;0;-4}    d) (2x + 3)  vdots (3x + 2)   => 3(2x+3)  vdots (3x + 2)   => 6x + 9  vdots 3x + 2   => 6x + 4 + 5  vdots 3x + 2   => 2(3x+2) + 5  vdots 3x + 2   Do 2(3x+2)  vdots 3x + 2   => 5  vdots 3x + 2   => 3x + 2 &isin; Ư(5) = {&plusmn;1;&plusmn;5}    => x &isin; {frac{-1}{3};-1;1;frac{-7}{3}    Vậy x &isin; {frac{-1}{3};-1;1;frac{-7}{3}}