ĐKXĐ (nếu bạn cần ): \(x\ne0;x\ne34\)
D
\(A=\left\{x\in N|x=2k;53< k\le62\right\}\)
Khi
\(\dfrac{1}{-1+x}\ge0\)
\(1\ge x-1\)
\(x\le2\)
=\(x^2+2.3.x+3^2=\left(x+3\right)^2\)