Expanding double brackets

Example: Expand using the grid method

Draw a grid with two rows and two columns, since we have two terms in each set of brackets:

Now, multiply each term in the first set of brackets by each term in the second set of brackets (with the grid method, this is as simple as filling in each box by multiplying the row and column headers):

Remember: The and headers multiply to give positive ,

Add the terms in the middle of the grid together to get the final answer:

• Answer: