The absolute value 
returns the "positive version" of a number.
In other words, if the number is positive, it remains positive; if the number is negative, it changes sign.
So, if we want 
, we want the "positive version" of x to be 9.
This can happen in two ways: if x is already 9, then its absolute value is still nine. If instead x=-9, its positive value will be 9 again.
In formula, we have
because
Answer:
D. 3x² + 19x - 14
Step-by-step explanation:
Use FOIL to find the answer.
First: x * 3x = 3x²
Outer: -2 * x = -2x
Inner: 3x * 7 = 21x
Last: 7 * -2 = -14
Form the equation:
3x² - 2x + 21x - 14
Combine like terms.
3x² + 19x - 14
Cindy needs to buy 8 packs of invitations.
