tìm x a)5x+65=-110 b)x+30%x=-1,3 c)l2/3x+1l=5/4 giúp mk với

0 bình luận về “tìm x a)5x+65=-110 b)x+30%x=-1,3 c)l2/3x+1l=5/4 giúp mk với”

1. a) 5x + 65 = -110

   5x = -110 – 65

   5x = -175

   x = -175 : 5

   x = -35

   b) x + 30%x = -1,3

   x + $\frac{3}{10}$x = $\frac{-13}{10}$

   x(1 + $\frac{3}{10}$) = $\frac{-13}{10}$

   x . $\frac{13}{10}$ = $\frac{-13}{10}$

   x = $\frac{-13}{10}$ : $\frac{13}{10}$

   x = -1

   c) |$\frac{2}{3}$x + 1| = $\frac{5}{4}$

   => $\frac{2}{3}$x + 1 = $\frac{5}{4}$ hoặc $\frac{-5}{4}$

   TH1 : $\frac{2}{3}$x + 1 = $\frac{5}{4}$

   $\frac{2}{3}$x = $\frac{5}{4}$ – 1

   $\frac{2}{3}$x = $\frac{5}{4}$ – $\frac{4}{4}$

   $\frac{2}{3}$x = $\frac{1}{4}$

   x = $\frac{1}{4}$ : $\frac{2}{3}$

   x = $\frac{1}{4}$ x $\frac{3}{2}$

   x = $\frac{3}{8}$

   TH2 : $\frac{2}{3}$x + 1 = $\frac{-5}{4}$

   $\frac{2}{3}$x = $\frac{-5}{4}$ – 1

   $\frac{2}{3}$x = $\frac{-5}{4}$ – $\frac{4}{4}$

   $\frac{2}{3}$x = $\frac{-9}{4}$

   x = $\frac{-9}{4}$ : $\frac{2}{3}$

   x = $\frac{-9}{4}$ x $\frac{3}{2}$

   x = $\frac{-27}{8}$

   Bình luận

2. Đáp án:

   a)5x+65=-110

   5x=-110-65

   5x=-175

   x=-175:5

   x=-35

   b)x+30%x=-1,3

   x+0,3*x=-1,3

   (1+0,3)*x=-1,3

   1,3*x=-1,3

   x=-1,3:1,3

   x=-1

   c)|2/3x+1l=5/4

   #2/3x+1=5/4

   2/3x=5/4-1

   2/3x=1/4

   x=1/4:2/3

   x=8/3

   #2/3x+1=-5/4

   2/3x=-5/4-1

   2/3x=-9/4

   x=-9/4:2/3

   x=-27/8

    

   Bình luận