Toán Lớp 7: /x-`4/3`/-`2/5`=`3/5` b,/x-`1/3`-/3x+`1/4`/=0 DẤU / LÀ DẤU GTTĐ NHA

Question

Toán Lớp 7:  /x-4/3/-2/5=3/5 b,/x-1/3-/3x+1/4/=0  DẤU / LÀ DẤU GTTĐ NHA

tuminh25 · Answer

Giải đáp+Lời giải và giải thích chi tiết:   a. lx-4/3l-2/5=3/5   lx-4/3l=3/5+2/5   lx-4/3l=1   x-4/3=1    hoặc    x-4/3=-1   x=1+4/3               x=-1+4/3   x=7/3                    x=1/3   V&acirc;̣y x &isin; {1/3;7/3}   b. lx-1/3l-l3x+1/4l=0   lx-1/3l=l3x+1/4l   TH1:   x-1/3=3x+1/4   x-3x=1/4+1/3   -2x=7/12   x=7/12:(-2)   x=-7/24   TH2:   -(x-1/3)=3x+1/4   1/3-x=3x+1/4   1/3-1/4=3x+x   1/12=4x   x=1/12:4   x=1/48   V&acirc;̣y x &isin; {-7/24;1/48}

myngocla · Answer

Giải đáp:     a) x&isin;{7/3;1/3}   b) x&isin;{- 7/24;1/48}     Lời giải và giải thích chi tiết:     a) |x-4/3|-2/5=3/5   &rarr;|x-4/3|=1   &rarr; ( left[  begin{array}{l}x- dfrac{4}{3}=1  x- dfrac{4}{3}=-1 end{array}  right. )    &rarr; ( left[  begin{array}{l}x= dfrac{7}{3}  x= dfrac{1}{3} end{array}  right. )    Vậy: x&isin;{7/3;1/3}   b) |x-1/3|-|3x+1/4|=0   &rarr;|x-1/3|=|3x+1/4|   &rarr; ( left[  begin{array}{l}x- dfrac{1}{3}=3x+ dfrac{1}{4}  x- dfrac{1}{3}=-3x- dfrac{1}{4} end{array}  right. )    &rarr; ( left[  begin{array}{l}x-3x= dfrac{1}{3}+ dfrac{1}{4}  x+3x= dfrac{1}{3}- dfrac{1}{4} end{array}  right. )    &rarr; ( left[  begin{array}{l}-2x= dfrac{7}{12}  4x= dfrac{1}{12} end{array}  right. )    &rarr; ( left[  begin{array}{l}x=- dfrac{7}{24}  x= dfrac{1}{48} end{array}  right. )    Vậy: x&isin;{- 7/24;1/48}