Question

1. Tìm x , biết :

a) |2x - 5| = -4

b) \(\dfrac{1}{3}\) - |\(\dfrac{5}{4}-2x\)| = \(\dfrac{1}{4}\)

c) \(\dfrac{1}{2}\) - |\(x+\dfrac{1}{5}\)| = \(\dfrac{1}{3}\)

d) \(\dfrac{3}{4}\) - | 2x + 1 | = \(\dfrac{7}{8}\)

Answer 1

a) Ta có: |2x-5| \(\ge\)0 với mọi x

mà |2x-5|=-4

=> x\(\in\varnothing\)

b)\(\dfrac{1}{3}-\left|\dfrac{5}{4}-2x\right|=\dfrac{1}{4}\)

=>\(\left|\dfrac{5}{4}-2x\right|=\dfrac{1}{3}-\dfrac{1}{4}=\dfrac{1}{12}\)

=>\(\left[{}\begin{matrix}\dfrac{5}{4}-2x=\dfrac{1}{12}\\\dfrac{5}{4}-2x=-\dfrac{1}{12}\end{matrix}\right.=>\left[{}\begin{matrix}2x=\dfrac{5}{4}-\dfrac{1}{12}=\dfrac{7}{6}\\2x=\dfrac{5}{4}+\dfrac{1}{12}=\dfrac{4}{3}\end{matrix}\right.\)=>\(\left[{}\begin{matrix}x=\dfrac{7}{12}\\x=\dfrac{2}{3}\end{matrix}\right.\)

phần c và d cũng tương tự bạn tự làm nha

Answer 2

Toàn bài dễ, suy nghĩ ik bn

Answer 3

cái này cx k hiểu nữa