Question

Tìm số nguyên x, biết:
a) 6x+2 chia hết cho 3x+4
b) -3x+5 chia hết cho 2x-1
c) 5-2x+x² chia hết cho 3x+4

Answer 1

a: \(\Leftrightarrow6x+8-6⋮3x+4\)

\(\Leftrightarrow3x+4\in\left\{1;-1;2;-2;3;-3;6;-6\right\}\)

hay \(x\in\left\{-1;-\dfrac{5}{3};-\dfrac{2}{3};-2;-\dfrac{1}{3};-\dfrac{7}{3};\dfrac{2}{3};-\dfrac{10}{3}\right\}\)

b: \(\Leftrightarrow-6x+10⋮2x-1\)

\(\Leftrightarrow2x-1\in\left\{1;-1;7;-7\right\}\)

hay \(x\in\left\{1;0;4;-3\right\}\)