Factoring trinomials with the box method

Factoring trinomials with the box method

By Cassandra Cook

It will look like this when we're done

​Our goal is to find out how to turn

3x²-x-2 into (3x-2)(x+1) using the same boxes that we did before.

First set up your grid and put the first term and the last term in the first full box and the last full box.​

3x²+x-2

​To figure that out, we need to find the pair of numbers that multiplies to be the first number times the last, but adds to the middle number.

​

​Some text here about the topic of discussion.

The tough part is we need to figure out what goes in the other two full boxes.​

​

What pair of numbers multiplies to be -6 but adds to 1?

​

Multiple Choice

What pair of numbers multiplies to be -6 but adds to 1?

• -3, 2

• 3, -2

• 3, 2

• -3, -2

Order doesn't matter!

​

​Some text here about the topic of discussion.

​Put these numbers with a variable in the remaining boxes

​Find the greatest common factor of each row and column.

Multiple Choice

Which grid correctly finds the greatest common factors of each row and column?

Multiple Choice

Next we take the outsides of the grid where the problems are and set up our parentheses ( )( ). Which set of ( )( ) correctly matches the grid?

• (x-1)(3x+2)

• $$3x^2-2x+3x-2$$  

• (3x-2)(x+1)

• (3x-2)(x+1)( $$3x^2$$  -2x)(3x-2)

Draw

Use your new skills to do as much of the box as possible. Factor

x²+7x+12

Draw

Use your new skills to do as much of the box as possible. Factor

12x²-11x-2