Toán Lớp 7: Tìm x: 1, ║x-3 ║=2x-5 ║n ║là giá trị tuyệt đối nha

Question

Toán Lớp 7:  Tìm x: 1, ║x-3 ║=2x-5  ║n ║là giá trị tuyệt đối nha

khanhngantoan · Answer

| x - 3| = 2x - 5   =>  ( left[  begin{array}{l}2x - 5 = x - 3  2x - 5 = -x + 3 end{array}  right. )    => ( left[  begin{array}{l}2x - 5 - x = -3  2x + x - 5 = 3 end{array}  right. )    => ( left[  begin{array}{l}x - 5=-3  3x - 5 = 3 end{array}  right. )    => ( left[  begin{array}{l}x =2  3x = 8 end{array}  right. )    => ( left[  begin{array}{l}x=2  x=8/3 end{array}  right. )    Vậy x &isin; { 2 ; 8/3 }

mocmien87 · Answer

Giải đáp:    $ left  { {{2x-5&ge;0}  atop { left[  begin{array}{l}x-3=2x-5  x-3=-(2x-5) end{array}  right.}}  right.$&hArr;$ left  { {{2x&ge;5}  atop { left[  begin{array}{l}x-2x=-5+3  x+2x=5+3 end{array}  right.}}  right.$&hArr;$ left  { {{x&ge;5/2}  atop { left[  begin{array}{l}-1x=-2  3x=8 end{array}  right.}}  right.$ &hArr;$ left  { {{x&ge;5/2}  atop { left[  begin{array}{l}x=2(loại)  x=8/3 end{array}  right.}}  right.$    Vậy x=8/3   Ch&uacute;c bạn HT~