Simplifying the Expression (x+7)(x-2)-(x+9)(x-4)
This article will guide you through simplifying the expression (x+7)(x-2)-(x+9)(x-4). We'll break down each step to understand the process clearly.
Expanding the Expressions
The first step is to expand the two products using the FOIL (First, Outer, Inner, Last) method.
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(x+7)(x-2):
- First: x * x = x²
- Outer: x * -2 = -2x
- Inner: 7 * x = 7x
- Last: 7 * -2 = -14
- Combined: x² -2x + 7x - 14 = x² + 5x - 14
-
(x+9)(x-4):
- First: x * x = x²
- Outer: x * -4 = -4x
- Inner: 9 * x = 9x
- Last: 9 * -4 = -36
- Combined: x² - 4x + 9x - 36 = x² + 5x - 36
Combining Like Terms
Now, we can substitute the expanded expressions back into the original equation:
(x² + 5x - 14) - (x² + 5x - 36)
Remember that subtracting a whole expression means changing the sign of each term within it:
x² + 5x - 14 - x² - 5x + 36
Finally, we combine like terms:
- x² - x² = 0
- 5x - 5x = 0
- -14 + 36 = 22
Final Result
The simplified expression is 22.
Therefore, (x+7)(x-2)-(x+9)(x-4) = 22.
This example showcases how using the FOIL method and combining like terms can simplify complex expressions. It's important to remember the sign rules when dealing with parentheses and subtraction.