Toán Lớp 7: Tìm x biết A) |x +¼|- ¾ =5% b) 2-|3/2 x- ¼|=|-5/4| C) 3/2+4/5|x-¾|=7/4 d) 4,5 – ¾|½ x + 5/3| = 5/6

Question

Toán Lớp 7:  Tìm x biết  A) |x +¼|- ¾ =5%                      b) 2-|3/2 x- ¼|=|-5/4|  C) 3/2+4/5|x-¾|=7/4               d) 4,5 – ¾|½ x + 5/3| = 5/6

behocgioitoan · Answer

Giải đáp:   Bạn tham khảo đ&aacute;p &aacute;n b&ecirc;n dưới nh&eacute;!   Lời giải và giải thích chi tiết:   a)   $ left|x+ dfrac14 right|- dfrac34=5 %   Rightarrow  left|x+ dfrac14 right|- dfrac34= dfrac{1}{20}   Rightarrow  left|x+ dfrac14 right|= dfrac45   Rightarrow  left { begin{matrix}x+ dfrac14= dfrac45  x+ dfrac14= dfrac{-4}{5} end{matrix} right.   Rightarrow  left { begin{matrix}x= dfrac{11}{20}  x= dfrac{-21}{20} end{matrix} right.$   b)    $2- left| dfrac32x- dfrac14 right|= left| dfrac{-5}{4} right|   Rightarrow 2- left| dfrac32x- dfrac14 right|= dfrac{5}{4}   Rightarrow  left| dfrac32x- dfrac14 right|= dfrac34   Rightarrow left { begin{matrix} dfrac32x- dfrac14= dfrac34   dfrac32x- dfrac14= dfrac{-3}{4} end{matrix} right.   Rightarrow left { begin{matrix}x= dfrac23  x= dfrac{-1}{3} end{matrix} right.$   c)   $ dfrac32+ dfrac45 cdot left|x- dfrac34 right|= dfrac74   Rightarrow  dfrac45 cdot left|x- dfrac34 right|= dfrac14   Rightarrow left|x- dfrac34 right|= dfrac{5}{16}   Rightarrow  left {  begin{array}{l}x- dfrac34= dfrac5{16}  x- dfrac34= dfrac{-5}{16} end{array}  right.   Rightarrow left { begin{array}{l}x= dfrac{17}{16}  x= dfrac{7}{16} end{array}  right.$   d)    $4,5- dfrac34 cdot left| dfrac12x+ dfrac53 right|= dfrac56   Rightarrow  dfrac34 cdot left| dfrac12x+ dfrac53 right|= dfrac{11}{3}   Rightarrow  left| dfrac12x+ dfrac53 right|= dfrac{44}{9}   Rightarrow left { begin{array}{l} dfrac12x+ dfrac53= dfrac{44}9   dfrac12x+ dfrac53= dfrac{-44}{9} end{array}  right.   Rightarrow left { begin{array}{l}x= dfrac{58}{9}  x= dfrac{-118}{9} end{array}  right.$