Toán Lớp 7: Tìm x: a,5-|3x-1|=3 b,(1-2x)^2=9

Question

Toán Lớp 7:  Tìm x: a,5-|3x-1|=3  b,(1-2x)^2=9

dinhcongson · Answer

Giải đáp+Lời giải và giải thích chi tiết:   a)   5-|3x-1|=3   &hArr;|3x-1|=2   &hArr; ( left[  begin{array}{l}3x-1=2  3x-1=-2 end{array}  right. )    &hArr; ( left[  begin{array}{l}x=1  x= frac{-1}{3} end{array}  right. )    Vậy S={1,-1/3}   b)   (1-2x)^2=9   &hArr;(1-2x)^2=3^2   &hArr; ( left[  begin{array}{l}1-2x=3  1-2x=-3 end{array}  right. )    &hArr; ( left[  begin{array}{l}x=-1  x=2 end{array}  right. )    Vậy  S={-1,2}

tongtung · Answer

a)  5 - |3x - 1| = 3   &rArr; |3x - 1|       = 5 - 3   &rArr; |3x - 1|       = 2   &rArr; $ left[  begin{array}{l}3x - 1 = 2  3x - 1=-2 end{array}  right.$   &rArr; $ left[  begin{array}{l}3x = 3   3x = -1 end{array}  right.$   &rArr; x = 1       x = $ dfrac{-1}{3}$   b) (1 - 2x)&sup2; = 9   &rArr; (1 - 2x)&sup2; = 3&sup2;   &rArr; $ left[  begin{array}{l}1 - 2x = 3  1 - 2x=-3 end{array}  right.$   &rArr; $ left[  begin{array}{l} 2x = -2  2x= -4 end{array}  right.$   &rArr; $ left[  begin{array}{l} x = -1  x= -2 end{array}  right.$