Đáp án:
$|7/8x+5/6|-|1/2x+5| = 0$
TH1: $7/8x+5/6 ≥ 0; 1/2x+5 ≥ 0$
$⇔ 7/8x+5/6 - (1/2x+5) =0$
$⇔ 7/8x + 5/6 - 1/2x - 5 = 0$
$⇔ 0,375x - 25/6 = 0$
$⇔ 0,375x = 25/6 $
$⇔ x = 100/9$ (nhận)
$TH2: 7/8x+5/6 ≥ 0; 1/2x+5 < 0$
$⇔ 7/8x+5/6 - (-1/2x-5) = 0 $
$⇔ 7/8x + 5/6 + 1/2x + 5 =0 $
$⇔ 1,375x + 35/6 =0$
$⇔ 1,375x = -35/6$
$⇔ x= -140/33$ (nhận)
$TH3: 7/8x+5/6<0; 1/2x+5 ≥ 0$
$⇔ -7/8x-5/6-(1/2x+5)=0$
$⇔ -7/8x-5/6-1/2x-5=0$
$⇔ -11/8x - 35/6 = 0 $
$⇔ -11/8x = 35/6$
$⇔ x = -140/33$ (nhận)
$TH4: 7/8x+5/6<0; 1/2x+5<0$
$⇔ -7/8x-5/6-(-1/2x-5)=0$
$⇔ -7/8x-5/6+1/2x+5=0$
$⇔ -3/8x + 25/6 =0$
$⇔ -3/8x = -25/6$
$⇔ x=100/9$ (nhận)
Vậy $S=${$100/9; -140/33$}
BẠN THAM KHẢO NHA!!!
