Factor each expression below.

1. $x^2+8x$ 

   Hint (a):

   Look for a greatest common factor.

2. $x^2y^2−81z^2$ 

   Hint (b):

   This is the difference of squares:

   $(xy)^2 - (9z)^2$

   More Help (b):

   If you need more help, look up difference of squares in the glossary or find your class work from Lesson 3.1.2.

3. $2x^2+14x−16$ 

   Hint (c):

   Always start by looking for a greatest common factor.

   More Help (c):

   Can you factor the polynomial further?

4. $3x^2−11x−4$ 

   Hint (d):

   Use a generic rectangle. Remember that the products of the diagonals must be equal.

   Step 1(d):

   . Image of 2 by 2 rectangle.

   Start by filling in the first and last terms.

   Added to interior labeled, top left, 3, x squared, bottom right, negative 4. 

   Step 2(d):

   What two numbers multiply to $−12$ and add to $−11$?  Added to rectangle, interior labels, top right, 1, x, bottom left, negative 12, x.

   Step 3(d):

   Find the greatest common factor for each row and column.Added to rectangle, labels, left edge, top & bottom, each with question mark, bottom edge, left, 3, x, right, + 1.

   Answer (d):

   $3x^2-11x-4=(3x+1)(?+?)$