Avoid messy scans or incomplete collections. You need and detailed corrigés . Here are the gold standards:

are known to share educational resources and PDF links specifically for MPSI/PCSI students. specific chapters

Now open the Methode section of the PDF for that chapter. Read the "Recette de cuisine mathématique" (the recipe). For example: "Calcul d’une intégrale impropre – Etape 1 : Vérifier la convergence absolue. Etape 2 : Chercher une primitive. Etape 3 : Faire tendre vers les bornes."