S=2(4x+2x)+4x^2=4x^2+12x
4x^2+12x=7
4x^2+12x-7=0
D=12^2-4x4x(-7)=256
X1=(-12-16)/(2x4)=-3.5 impossible
X2=(-12+16)/(2x4)=0.5
A
Answer:
1.5 hours
Step-by-step explanation:
The ratio is 8:1, 8 being presents, one being hours. Half of 8 is 4, and eight +4 is 12, so it needs to be an hour and a half.
If you ride x miles, the price y will be:
y=1.5+0.35x
You can ride any number of miles you want. But what you can't ride negative miles.
So negative numbers are not reasonable domain values.
Insert 4 for x and 2 for y in the equation
6(4) - (2)^2
24 - 4 = 20