Factor 56x² - 14x

Factor 56x² - 14x - 7

Here we will show you how to factor the quadratic function 56x² - 14x - 7 using the box method. In other words, we will show you how to factor 56x squared minus 14x minus 7 (56x^2 - 14x - 7) 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 56x² - 14x - 7, like this:

a = 56
b = -14
c = -7

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

-7	-28x	-7
14x	56x²	14x
	4x	1

We put 56x² (a) in the bottom left square and -7 (c) in the top right square, like this:

-7	-28x	-7
14x	56x²	14x
	4x	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 56 times -7 (a × c), and add together to equal -14 (b).

More specifically, 56 times -7 is -392. Therefore, we need to find the two numbers that multiply to equal -392, and add to equal -14.

? × ? = -392
? + ? = -14

After looking at this problem, we can see that the two numbers that multiply together to equal -392, and add together to equal -14, are -28 and 14, as illustrated here:

-28 × 14 = -392
-28 + 14 = -14

Now, we can fill in the last two squares in our box with -28x and 14x. Place -28x in the upper left square, and place 14x in the lower right square.

-7	-28x	-7
14x	56x²	14x
	4x	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 -28x and -7. The greatest common factor of -28x and -7 is -7. Therefore, we write -7 to the left of the top row. You can see it here in the color green:

-7	-28x	-7
14x	56x²	14x
	4x	1

Next, let’s look at the bottom row. We have the terms 56x² and 14x. The greatest common factor of 56x² and 14x is 14x. Therefore, we write 14x to the left of the bottom row. You can see it here in the color blue:

-7	-28x	-7
14x	56x²	14x
	4x	1

To find the values below the table, we first divide 56x² by 14x (labeled in blue). This gives us 4x.

56x² ÷ 14x = 4x

You can see this value colored in orange below:

-7	-28x	-7
14x	56x²	14x
	4x	1

Next, we divide 14x by 14x (labeled in blue). This gives us 1.

14x ÷ 14x = 1

You can see this value colored in purple below:

-7	-28x	-7
14x	56x²	14x
	4x	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 56x² - 14x - 7. 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:

(14x - 7)(4x + 1)

That’s it! Now you know how to factor the equation 56x² - 14x - 7.

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