Factor 17x² + 56x + 39

Here we will show you how to factor the quadratic function 17x² + 56x + 39 using the box method. In other words, we will show you how to factor 17x squared plus 56x plus 39 (17x^2 + 56x + 39) 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 17x² + 56x + 39, like this:

a = 17
b = 56
c = 39

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

1	17x	39
x	17x²	39x
	17x	39

We put 17x² (a) in the bottom left square and 39 (c) in the top right square, like this:

1	17x	39
x	17x²	39x
	17x	39

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 17 times 39 (a × c), and add together to equal 56 (b).

More specifically, 17 times 39 is 663. Therefore, we need to find the two numbers that multiply to equal 663, and add to equal 56.

? × ? = 663
? + ? = 56

After looking at this problem, we can see that the two numbers that multiply together to equal 663, and add together to equal 56, are 17 and 39, as illustrated here:

17 × 39 = 663
17 + 39 = 56

Now, we can fill in the last two squares in our box with 17x and 39x. Place 17x in the upper left square, and place 39x in the lower right square.

1	17x	39
x	17x²	39x
	17x	39

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 17x and 39. The greatest common factor of 17x and 39 is 1. Therefore, we write 1 to the left of the top row. You can see it here in the color green:

1	17x	39
x	17x²	39x
	17x	39

Next, let’s look at the bottom row. We have the terms 17x² and 39x. The greatest common factor of 17x² and 39x is x. Therefore, we write x to the left of the bottom row. You can see it here in the color blue:

1	17x	39
x	17x²	39x
	17x	39

To find the values below the table, we first divide 17x² by x (labeled in blue). This gives us 17x.

17x² ÷ x = 17x

You can see this value colored in orange below:

1	17x	39
x	17x²	39x
	17x	39

Next, we divide 39x by x (labeled in blue). This gives us 39.

39x ÷ x = 39

You can see this value colored in purple below:

1	17x	39
x	17x²	39x
	17x	39

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 17x² + 56x + 39. 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:

(x + 1)(17x + 39)

That’s it! Now you know how to factor the equation 17x² + 56x + 39.

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