Question

tìm x

a, | 5/4x - 7/2 | - | 5/8x + 3/5 | = 0

b, 21/5 + 3 : | x/4 - 2/3 | = 6

c,| 9 + x | = 2x

d, | 2x - 3 | + x = 21

e, | 7 - 2x | + 7 = 2x

f, | -x + 2/5 | + 1/2 = 3,5

G, | 3x - 4 | + 4 = 3x

Answer 1

a: =>|5/4x-7/2|=|5/8x+3/5|

=>5/4x-7/2=5/8x+3/5 hoặc 5/4x-7/2=-5/8x-3/5

=>5/8x=41/10 hoặc 15/8x=29/10

=>x=164/25 hoặc x=116/75

b: =>3:|x/4-2/3|=6-21/5=9/5

=>|1/4x-2/3|=5/3

=>1/4x-2/3=5/3 hoặc 1/4x-2/3=-5/3

=>1/4x=7/3 hoặc 1/4x=-1

=>x=28/3 hoặc x=-4

c: \(\Leftrightarrow\left\{{}\begin{matrix}x>=0\\\left(2x-x-9\right)\left(2x+x+9\right)=0\end{matrix}\right.\Leftrightarrow x=9\)

e: =>|2x-7|=2x-7

=>2x-7>=0

=>x>=7/2