Answer:
$45.22
Step-by-step explanation:
The number of miles per gallon can be represented by the ratio:
Since we know the unit rate of 26 miles per gallon of gas, we can set up a proportion, or equivalent ratios, to find the number of gallons needed for 420 miles:
, where 'x' is the number of gallons of gas
cross-multiply and divide: 26x = 420 or x ≈ 16.15 gallons
If gas is $2.80 per gallon, take the total number of gallons needed and multiply by $2.80:
16.15 x $2.80 = $45.22
Answer:
Step-by-step explanation:
A parabola is written in the form
(1)
where:
is the x-coordinate of the vertex of the parabola
is the y-coordinate of the vertex of the parabola
is a scale factor
For the parabola in the problem, we know that the vertex has coordinates (4,-3), so we have:
(2)
From this last equation, we get that (3)
Substituting (2) and (3) into (1) we get the new expression:
(4)
We also know that the parabola contains the point (2,-1), so we can substitute
x = 2
f(x) = -1
Into eq.(4) and find the value of k:
So we also get:
So the equation of the parabola is:
(5)
Now we want to rewrite it in the standard form, i.e. in the form
To do that, we simply rewrite (5) expliciting the various terms, we find: