1st we should find the point where the line intersects with the axises
put x= 0 , so y= 3 ---- > the 1st point (0,3)
put y=0 , so x = 7.5 ----> the 2nd point (7.5,0)
so it's the first graph on the left
We are trying to find the average speed of the plane, which is mph, or 
. Using proportions, we can find the average speed of the plane in mph:
- Use the information from the problem to create a proportion. Remember that we are looking for mph, so we will call that
.
- Multiply the entire equation by
- Divide both sides of the equation by
to clear both sides of the mile unit
The average speed of the plane is 300 mph.
The circumference of the circle
is given by the equation C = pi * D. Incorporating the length of the diameter
into the equation, we have,
C = pi * D
C =
pi * 7cm
C =
21.99 cm
<span>We can safely assume that 1212 is a misprint and the number of seats in a row exceeds the number of rows by 12.
Let r = # of rows and s = # of seats in a row.
Then, the total # of seats is T = r x s = r x ( r + 12), since s is 12 more than the # of rows.
Then
r x (r + 12) = 1564
or
r**2 + 12*r - 1564 = 0, which is a quadratic equation.
The general solution of a quadratic equation is:
x = (-b +or- square-root( b**2 - 4ac))/2a
In our case, a = 1, b = +12 and c = -1564, so
x = (-12 +or- square-root( 12*12 - 4*1*(-1564) ) ) / 2*1
= (-12 +or- square-root( 144 + 6256 ) ) / 2
= (-12 +or- square-root( 6400 ) ) / 2
= (-12 +or- 80) / 2
= 34 or - 46
We ignore -46 since negative rows are not possible, and have:
rows = 34
and
seats per row = 34 + 12 = 46
as a check 34 x 46 = 1564 = total seats</span>
