Institutions: Global | Ekurhuleni Libraries | Joburg Libraries | Tshwane Libraries | Invest in Zim

MathsGee is Zero-Rated (You do not need data to access) on: Telkom |Dimension Data | Rain | MWEB

0 like 0 dislike
23 views
How do I decompose $x^2-9$ using the distributive property?
| 23 views

0 like 0 dislike
It can also be said of an expression such as $x^2 − 9$ that it does not seem to match $xy + xz$. However, we can decompose the expression $x^2 − 9$ as shown below:

$x^2 − 9$

$= x^2 + 0x − 9$  (adding $0x$ to the expression $x^2 − 9$ does not change its value)

$= x^2 + 3x − 3x − 9$  ($+3x − 3x = 0; + 3x$ and $−3x$ are additive inverses)

$= x \cdot x + 3x − 3x + 3 \cdot 3$

$= x(x + 3) − 3(x + 3)$

$= (x + 3)(x − 3)$
by Diamond (61,678 points)

0 like 0 dislike