Question

Answer 1

\(1,A=-\left(x^2-6x+9\right)+9=-\left(x-3\right)^2+9\le9\\ A_{max}=9\Leftrightarrow x=3\\ 2,B=-\left(x^2+8x+16\right)+24=-\left(x+4\right)^2+24\le24\\ B_{max}=24\Leftrightarrow x=-4\\ 3,C=\left(4x^2+8x+4\right)+6=4\left(x+1\right)^2+6\ge6\\ C_{min}=6\Leftrightarrow x=-1\\ 4,A=\left(2x^2+8x+8\right)+3=2\left(x+2\right)^2+3\ge3\\ A_{min}=3\Leftrightarrow x=-2\)