This is the 15330th most frequent Polish word.
skuteczną
"Effective."
Here, 'skuteczną' is the feminine singular accusative form of the adjective 'skuteczny,' agreeing with the noun 'strategię' (strategy), indicating an objective that is effective.
Potrzebujemy skuteczną strategię.
We need an effective strategy.
In this context, 'skuteczną' modifies the noun 'metodę' (method), which is in the feminine singular accusative case, describing the method as effective.
Znaleźliśmy skuteczną metodę nauki.
We found an effective learning method.
'Skutecznej' is used here as the feminine singular genitive form of 'skuteczny' to agree with 'terapii' (therapy) in a genitive phrase following the noun 'Wprowadzenie' (Introduction/Implementation).