Factor 4x² + 24x + 35

Here we will show you how to factor the quadratic function 4x² + 24x + 35 using the box method. In other words, we will show you how to factor 4x squared plus 24x plus 35 (4x^2 + 24x + 35) using the box method. It is a 5-step process:

Step 1: The standard form of a quadratic equation is ax² + bx + c. We start by labeling the different parts of our equation 4x² + 24x + 35, like this:

a = 4
b = 24
c = 35

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

5	10x	35
2x	4x²	14x
	2x	7

We put 4x² (a) in the bottom left square and 35 (c) in the top right square, like this:

5	10x	35
2x	4x²	14x
	2x	7

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 4 times 35 (a × c), and add together to equal 24 (b).

More specifically, 4 times 35 is 140. Therefore, we need to find the two numbers that multiply to equal 140, and add to equal 24.

? × ? = 140
? + ? = 24

After looking at this problem, we can see that the two numbers that multiply together to equal 140, and add together to equal 24, are 10 and 14, as illustrated here:

10 × 14 = 140
10 + 14 = 24

Now, we can fill in the last two squares in our box with 10x and 14x. Place 10x in the upper left square, and place 14x in the lower right square.

5	10x	35
2x	4x²	14x
	2x	7

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 10x and 35. The greatest common factor of 10x and 35 is 5. Therefore, we write 5 to the left of the top row. You can see it here in the color green:

5	10x	35
2x	4x²	14x
	2x	7

Next, let’s look at the bottom row. We have the terms 4x² and 14x. The greatest common factor of 4x² and 14x is 2x. Therefore, we write 2x to the left of the bottom row. You can see it here in the color blue:

5	10x	35
2x	4x²	14x
	2x	7

To find the values below the table, we first divide 4x² by 2x (labeled in blue). This gives us 2x.

4x² ÷ 2x = 2x

You can see this value colored in orange below:

5	10x	35
2x	4x²	14x
	2x	7

Next, we divide 14x by 2x (labeled in blue). This gives us 7.

14x ÷ 2x = 7

You can see this value colored in purple below:

5	10x	35
2x	4x²	14x
	2x	7

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 4x² + 24x + 35. You simply put the values on the left in one set of parentheses, and the values below in another set of parentheses, to get the answer:

(2x + 5)(2x + 7)

That’s it! Now you know how to factor the equation 4x² + 24x + 35.

Factoring Quadratics
Go here if you want to learn how to factor another quadratic function.

Factor 4x² + 24x + 36
Here is the next quadratic function on our list that we have factored for you.