9.
I.在平面直角坐标系\(xOy \)中,曲线\({C}_{1} \)过点\(P\left(a,1\right) \)其参数方程为\(\begin{cases}x=a+ \sqrt{2}t \\ y=1+ \sqrt{2}t\end{cases} (t\)为参数,\(a∈R ).\)以点\(O\)为极点,\(X\)轴非负半轴为极轴,建立极坐标系,曲线\({C}_{2} \)的极坐标方程为\(ρ{\cos }^{2}θ+4\cos θ-ρ=0 \).
\((1)\)求曲线\({C}_{1} \)的普通方程和曲线\({C}_{2} \)的直角坐标方程;
\((2)\)已知曲线\({C}_{1} \)与曲线\({C}_{2} \)交于\(A\),\(B\)两点,且\(\left|PA\right|=2\left|PB\right| \)求实数\(A\)的值.
\(II.\)已知函数\(f\left(x\right)=\left|2x-a\right|+\left|x-1\right|,a∈R \).
\((1)\)若不等式\(f\left(x\right)\leqslant 2-\left|x-1\right| \)有解,求实数\(a\)的取值范围.
\((2)\)当\(a < 2 \)时,函数\(f\left(x\right) \)的最小值为\(3\),求实数\(a\)的值.