Factor -13x² - 24x

Factor -13x² - 24x - 11

Here we will show you how to factor the quadratic function -13x² - 24x - 11 using the box method. In other words, we will show you how to factor negative 13x squared minus 24x minus 11 (-13x^2 - 24x - 11) using the box method. It is a 5-step process:

Step 1: The standard form of a quadratic equation is ax² + bx + c. In this equation, a is negative. Therefore, we need to start by setting aside the negative (-). We do this by flipping the signs in the equation to get 13x² + 24x + 11. Now we can label the different parts of our equation, like this:

a = 13
b = 24
c = 11

Step 2: Next, we need to draw a box and divide it into four squares:

11	11x	11
13x	13x²	13x
	x	1

We put 13x² (a) in the bottom left square and 11 (c) in the top right square, like this:

11	11x	11
13x	13x²	13x
	x	1

Step 3: In order to fill in the other two squares, we need to do some math. We have to find two numbers that multiply together to give us the product of 13 times 11 (a × c), and add together to equal 24 (b).

More specifically, 13 times 11 is 143. Therefore, we need to find the two numbers that multiply to equal 143, and add to equal 24.

? × ? = 143
? + ? = 24

After looking at this problem, we can see that the two numbers that multiply together to equal 143, and add together to equal 24, are 11 and 13, as illustrated here:

11 × 13 = 143
11 + 13 = 24

Now, we can fill in the last two squares in our box with 11x and 13x. Place 11x in the upper left square, and place 13x in the lower right square.

11	11x	11
13x	13x²	13x
	x	1

Step 4: Next, we need to find four final numbers to finish factoring our equation. We can see that our box is a 2 x 2 table made up of rows and columns.

Our goal is to find the numbers that, when multiplied together, result in the products in each square. We can do this by finding the greatest common factor in each row.

Let’s look at the top row. We have the terms 11x and 11. The greatest common factor of 11x and 11 is 11. Therefore, we write 11 to the left of the top row. You can see it here in the color green:

11	11x	11
13x	13x²	13x
	x	1

Next, let’s look at the bottom row. We have the terms 13x² and 13x. The greatest common factor of 13x² and 13x is 13x. Therefore, we write 13x to the left of the bottom row. You can see it here in the color blue:

11	11x	11
13x	13x²	13x
	x	1

To find the values below the table, we first divide 13x² by 13x (labeled in blue). This gives us x.

13x² ÷ 13x = x

You can see this value colored in orange below:

11	11x	11
13x	13x²	13x
	x	1

Next, we divide 13x by 13x (labeled in blue). This gives us 1.

13x ÷ 13x = 1

You can see this value colored in purple below:

11	11x	11
13x	13x²	13x
	x	1

Step 5: Now we have all of the information we need to finish factoring the equation. The values outside of the box are used to factor -13x² - 24x - 11. You simply put the values on the left in one set of parentheses, and the values below in another set of parentheses, to get:

(13x + 11)(x + 1)

In our original quadratic equation, -13x² - 24x - 11, a is negative. Therefore, we need to add a negative (-) sign before our two sets of parentheses, like this:

-(13x + 11)(x + 1)

That’s it! Now you know how to factor the equation -13x² - 24x - 11.

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