已知函数\(f\left( x \right)=\left( {{m}^{2}}-m-1 \right){{x}^{4{{m}^{9}}-{{m}^{5}}-1}}\)是幂函数，对任意的\({{x}_{1}},{{x}_{2}}\in \left( 0,+\infty \right)\)，且\({{x}_{1}}\ne {{x}_{2}}\)，\(\left( {{x}_{1}}-{{x}_{2}} \right)\left[ f\left( {{x}_{1}} \right)-f\left( {{x}_{2}} \right) \right] > 0\)，若\(a,b\in R\)，且\(a+b > 0,ab < 0\)，则\(f\left( a \right)+f\left( b \right)\)的值\((\) \()\)