Let f(x)=(3+5x)2\displaystyle {f{{\left({x}\right)}}}={\left({3}+{5}{x}\right)}^{{2}}

f(x)\displaystyle {f{{\left({x}\right)}}} has one critical value at A =  

For x<A\displaystyle {x}<{A}, f(x)\displaystyle {f{{\left({x}\right)}}} is

For x>A\displaystyle {x}>{A}, f(x)\displaystyle {f{{\left({x}\right)}}} is