Toán Lớp 7: $ a ) ( 2x + 1 ) ( 3x + 3 ) = 0 $ $ b ) | x + 2 | + 2 = 2^3 $ $ c ) 2 . 3 . 6 + 3 . 4 . 5 + 12 . 2 $

Question

Toán Lớp 7:  $ a ) ( 2x + 1 ) ( 3x + 3 ) = 0 $ $ b ) | x + 2 | + 2 = 2^3 $  $ c ) 2 . 3 . 6 + 3 . 4 . 5 + 12 . 2 $

landinhngoc97 · Answer

Giải đáp:+lời giải        a)(2x+1)(3x+3)=0       &hArr; ( left[  begin{array}{l}2x+1=0  3x+3=0 end{array}  right. )        &hArr; ( left[  begin{array}{l}x=-1/2  x=-1 end{array}  right. )        vậy x=-1/2 hoặc x=-1       b) |x+2|+2=2&sup3;       &hArr;|x+2|=8-2=6       &hArr; ( left[  begin{array}{l}x+2=6  x+2=-6 end{array}  right. )        &hArr; ( left[  begin{array}{l}x=6-2=4  x=-6-2=-8 end{array}  right. )        vậy x=4 hoặc x=-8       c)2.3.6+3.4.5+12.2       =4.3.3+3.4.5+3.4.2       =3.4(3+5+2)       =3.4.10=120       xin hay nhất ạ

minhhaanh · Answer

a, (2x + 1)(3x + 3) = 0   =>  ( left[  begin{array}{l}2x+1=0  3x+3=0 end{array}  right. )    =>  ( left[  begin{array}{l}2x=-1  3x=-3 end{array}  right. )    =>  ( left[  begin{array}{l}x= dfrac{-1}{2}  x=-1 end{array}  right. )    Vậy x in {-1/2; -1}   b, |x + 2| + 2 = 2^3   => |x + 2| = 2^3 - 2   => |x + 2| = 8 - 2   => |x + 2| = 6   => [(x+2=6),(x+2=-6):} => [(x=4),(x=-8):}   c, 2.3.6 + 3.4.5 + 12.2   = 12.3 + 12.5 + 12.2   = 12. (3+5+2)   = 12.10   = 120