Answer: 
Step-by-step explanation:
All that is required here is to substitute x = 2x into the right side in the same way that is done for a numeric value.

Answer:
-12
Step-by-step explanation:
f(-3)= -(-3)2 + 6(-3)
= -(-6) -18
= 6 - 18
= - 12
minus 4 both sides
square both sides
x+2=4
minus 2
x=2
<span>the answer is
x = 2; not extraneous</span>
Answer:
Jur's car
Step-by-step explanation:
Jur's car's mileage= 340/12=28.3333333333
Jack's car's mileage=390/16=24.375
brainliest if you are satisfied plz