Answer: 
Step-by-step explanation:
1. By definition, you have if
, then 
2. Keeping this on mind, you must follow the proccedure shown below:
- You have that:

Where:

- Substitute values into
. Then, you obtain:
Answer:
x=3, -1/7
Step-by-step explanation:
7x^2-20x-3=0
Factor.
(x-3)(7x+1)=0
x-3=0 ⇒ x=3
7x+1=0 ⇒7x=-1 ⇒x= -1/7
You just divide. 38÷12=3.166~ $3.17