a.$−4y(5x+8y)$

• Step 1(a):

• Make and label a generic rectangle.

• 

• Step 2(a):

• Fill in the boxes, and then add the boxes' labels together

• 

• Answer (a):

• −20xy − 32y²

2. $9x(−4+10y)$

• Step 1(b):

• Distribute the 9x over each of the terms in the parentheses.

• 9x(−4) + 9x(10y)

• Step 2(b):

• Simplify.

• Answer (b):

• −36x + 90xy = 90xy − 36x

3. $(x^2−2)(x^2+3x+5)$

• Hint (c):

• Try using a generic rectangle to solve this problem.

• Answer (c):

• x⁴ + 3x³ + 3x² − 6x − 10