Multiplying Polynomials

To multiply a polynomial by a monomial use the Distributive Property.

    a ( b + c + d ) = ab + ac + ad

 

To multiply two binomials use the FOIL method.  

    F    the product of the first two terms

    O   the product of the outside terms

      the product of the inside terms

    L    the product of the last terms

    ( a + b )( c + d ) = ?

    F--- ac

    O--- ad

    I--- bc

    L--- bd

Thus, 

    ( a + b )( c + d ) = ac + ad + bc + bd

Then, combine like terms (if possible).

 

To multiply a polynomial by another polynomial multiply the second polynomial by each term in the first polynomial, then use the Distributive Property.  Finally, combine like terms (if possible).

    ( a + b + c )( d + e + f )= ?

    a( d + e + f ) + b( d + e + f ) + c( d + e + f )=

    ad + ae + af + bd + be + bf + cd + ce + cf

Thus, 

    ( a + b + c )( d + e + f ) = ad + ae + af + bd + be + bf + cd + ce + cf

Special Products of Polynomials

The following polynomials are very common in algebra.  Learning to recognize their forms and solutions would be very beneficial.

c( a + b ) = ca + cb

c( a - b ) = ca - cb

( a + b )2 = a2 + 2ab + b2

( a - b )2 = a2 - 2ab + b2

( a - b)(a + b) = a2 - b2

( a + c )( a + d ) = a2 + a(c + d) + cd