Toán Lớp 7: Tìm x A). -4/5 + 5/2x = -3/10 B). 1/2 -|5/4 -2x|= 1/3

Question

Toán Lớp 7:  Tìm x A).   -4/5 + 5/2x = -3/10 B).   1/2 -|5/4 -2x|= 1/3

tuyetnhungthu · Answer

Giải đáp + Lời giải và giải thích chi tiết:   A). -4/5 + 5/2x = -3/10                   5/2x = -3/10 - (-4/5)                   5/2x = 1/2                         x = 1/2 : 5/2                         x = 1/5   B). 1/2 -|5/4 -2x|= 1/3                |5/4 - 2x| = 1/2 - 1/3                |5/4 - 2x| = 1/6   &rArr; 5/4 - 2x = 1/6  hoặc  5/4 - 2x = -1/6                2x = 5/4 - 1/6            2x = 5/4 - (-1/6)                2x = 13/12                 2x = 17/12                  x = 13/12 : 2              x = 17/12 : 2                  x = 13/24                   x = 17/24   Vậy x &isin; { 13/24; 17/24 }

mocmien87 · Answer

Lời giải chi tiết:     a) -4/5+5/2x=-3/10   =>5/2x=-3/10-(-4/5)   =>5/2x=1/2   =>x=1/2:5/2   =>x=1/5   Vậy x=1/5   b) 1/2-|5/4-2x|=1/3   =>|5/4-2x|=1/2-1/3   =>|5/4-2x|=1/6   => ( left[  begin{array}{l} dfrac{5}{4}-2x= dfrac{1}{6}   dfrac{5}{4}-2x=- dfrac{1}{6} end{array}  right. )   => ( left[  begin{array}{l}2x= dfrac{5}{4}- dfrac{1}{6}  2x= dfrac{5}{4}+ dfrac{1}{6} end{array}  right. )   => ( left[  begin{array}{l}2x= dfrac{13}{12}  2x= dfrac{17}{12} end{array}  right. )   => ( left[  begin{array}{l}x= dfrac{13}{12}:2  x= dfrac{17}{12}:2 end{array}  right. )   => ( left[  begin{array}{l}x= dfrac{13}{24}  x= dfrac{17}{24} end{array}  right. )   Vậy x in{13/24;17/24}