4.
若正整数\(a\),\(b\),\(c\)满足\(\dfrac{1}{a}+\dfrac{1}{b}=\dfrac{1}{c}\),则称正整数\(a\),\(b\),\(c\)为一组和谐整数\(.\)例如,\(\dfrac{1}{24}+\dfrac{1}{12}=\dfrac{1}{24}+\dfrac{2}{24}=\dfrac{3}{24}\),\(\dfrac{1}{8}=\dfrac{3}{24}\)因此\(8\),\(12\),\(24\)是一组和谐整数
\((1)\)判断\(2\),\(3\),\(6\)是否是一组和谐整数,并说明理由;
\((2)\)已知\(x\),\(y\),\(z(\)其中\(x < y\leqslant z )\)是一组和谐整数.
\(①\)当\(x=6\),\(y=10\)时,求\(z\)的值.
\(②\)当\(x=m−2\),\(y=m+2\)时,试用含\(m\)的代数式表示\(z\).