13. It is actually faster here to compare like terms in x to find B and C . So always try to use the faster method. NEXT This makes B disappear, leaving only C . COVER-UP RULE COMPARING SUBSTITUTION
14. NEXT To check whether your partial fractions are correct, "combine" back the partial fractions on the RHS to see if you could obtain the algebraic fraction on the LHS. COVER-UP RULE COMPARING SUBSTITUTION
22. proper fraction now improper fraction (deg of numerator > deg of denominator) NEXT LONG DIVISION SPLITTING NUMERATOR
23. "introduce" denominator in the numerator improper fraction (deg of numerator = deg of denominator) split the numerator to create proper fraction NEXT LONG DIVISION SPLITTING NUMERATOR