Factoring and Expanding (x-10)(x-2)
This expression represents the product of two binomials: (x-10) and (x-2). We can analyze it in two ways:
Expanding the Expression
To expand the expression, we use the FOIL method (First, Outer, Inner, Last):
- First: Multiply the first terms of each binomial: x * x = x²
- Outer: Multiply the outer terms of the binomials: x * -2 = -2x
- Inner: Multiply the inner terms of the binomials: -10 * x = -10x
- Last: Multiply the last terms of each binomial: -10 * -2 = 20
Now, combine the terms:
x² - 2x - 10x + 20 = x² - 12x + 20
Therefore, the expanded form of (x-10)(x-2) is x² - 12x + 20.
Factoring the Expression
We can also factor the expression x² - 12x + 20 back into its original form:
- Find two numbers that multiply to 20 and add up to -12. These numbers are -10 and -2.
- Rewrite the middle term (-12x) using these numbers: x² - 10x - 2x + 20
- Factor by grouping: (x² - 10x) + (-2x + 20) x(x - 10) - 2(x - 10)
- Factor out the common binomial: (x - 10)(x - 2)
This confirms that the factored form of x² - 12x + 20 is (x-10)(x-2).
Applications
Understanding how to expand and factor binomials is crucial in algebra, especially when working with quadratic equations. It allows us to manipulate expressions and solve for unknown variables.