Question

[Cuồng Sơn Tùng M-tp]

Tìm x : a) |9-7x| = 5x-3

b) 8x - | 4x +1 | = x+2

c) | 17x - 5 | - | 17x + 5 | = 0

d) | 3x +4 | = 2 | 2x - 9 |

e) | 10x + 7 | < 37

f) |3-8x| ≤19

g) | x + 3 | - 2x = | x-4 |

Answer 1

[Nguyễn Lê Phước Thịnh]

a: =>|7x-9|=5x-3

\(\Leftrightarrow\left\{{}\begin{matrix}x>=\dfrac{3}{5}\\\left(7x-9-5x+3\right)\left(7x-9+5x-3\right)=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>=\dfrac{3}{5}\\\left(2x-6\right)\left(12x-12\right)=0\end{matrix}\right.\Leftrightarrow x\in\left\{1;3\right\}\)

b: \(\Leftrightarrow\left|4x+1\right|=8x-x-2=7x-2\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>=\dfrac{2}{7}\\\left(7x-2-4x-1\right)\left(7x-2+4x+1\right)=0\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}x>=\dfrac{2}{7}\\\left(3x-3\right)\left(11x-1\right)=0\end{matrix}\right.\Leftrightarrow x=1\)

c: |17x-5|=|17x+5|

=>17x-5=17x+5 hoặc 17x+5=5-17x

=>x=0