Question

Tìm x thuộc N sao cho:

a)x chia hết cho 4

b)x-3 chia hết cho x+1

c)2x-3 chia hết cho 7

Answer 1

a: =>\(x\in\left\{0;4;8;...\right\}\)

b: =>x+1-4 chia hết cho x+1

=>\(x+1\in\left\{1;2;4\right\}\)

=>\(x\in\left\{0;1;3\right\}\)

c: =>2x-3=7k(k\(\in N\))

=>2x=7k+3, \(k\in Z^+\)

=>\(\left\{{}\begin{matrix}k\in Z^+\\x=\dfrac{7k+3}{2}\end{matrix}\right.\)