Factor -45x² - 48x

Factor -45x² - 48x - 3

Here we will show you how to factor the quadratic function -45x² - 48x - 3 using the box method. In other words, we will show you how to factor negative 45x squared minus 48x minus 3 (-45x^2 - 48x - 3) 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 45x² + 48x + 3. Now we can label the different parts of our equation, like this:

a = 45
b = 48
c = 3

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

3	3x	3
45x	45x²	45x
	x	1

We put 45x² (a) in the bottom left square and 3 (c) in the top right square, like this:

3	3x	3
45x	45x²	45x
	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 45 times 3 (a × c), and add together to equal 48 (b).

More specifically, 45 times 3 is 135. Therefore, we need to find the two numbers that multiply to equal 135, and add to equal 48.

? × ? = 135
? + ? = 48

After looking at this problem, we can see that the two numbers that multiply together to equal 135, and add together to equal 48, are 3 and 45, as illustrated here:

3 × 45 = 135
3 + 45 = 48

Now, we can fill in the last two squares in our box with 3x and 45x. Place 3x in the upper left square, and place 45x in the lower right square.

3	3x	3
45x	45x²	45x
	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 3x and 3. The greatest common factor of 3x and 3 is 3. Therefore, we write 3 to the left of the top row. You can see it here in the color green:

3	3x	3
45x	45x²	45x
	x	1

Next, let’s look at the bottom row. We have the terms 45x² and 45x. The greatest common factor of 45x² and 45x is 45x. Therefore, we write 45x to the left of the bottom row. You can see it here in the color blue:

3	3x	3
45x	45x²	45x
	x	1

To find the values below the table, we first divide 45x² by 45x (labeled in blue). This gives us x.

45x² ÷ 45x = x

You can see this value colored in orange below:

3	3x	3
45x	45x²	45x
	x	1

Next, we divide 45x by 45x (labeled in blue). This gives us 1.

45x ÷ 45x = 1

You can see this value colored in purple below:

3	3x	3
45x	45x²	45x
	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 -45x² - 48x - 3. You simply put the values on the left in one set of parentheses, and the values below in another set of parentheses, to get:

(45x + 3)(x + 1)

In our original quadratic equation, -45x² - 48x - 3, a is negative. Therefore, we need to add a negative (-) sign before our two sets of parentheses, like this:

-(45x + 3)(x + 1)

That’s it! Now you know how to factor the equation -45x² - 48x - 3.

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