<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>
Answer:
Second choice:


Fifth choice:


Step-by-step explanation:
Let's look at choice 1.


I'm going to subtract 1 on both sides for the first equation giving me
. I will replace the
in the second equation with this substitution from equation 1.

Expand using the distributive property and the identity
:




So this not the desired result.
Let's look at choice 2.


Solve the first equation for
by dividing both sides by 2:
.
Let's plug this into equation 2:



This is the desired result.
Choice 3:


Solve the first equation for
by adding 3 on both sides:
.
Plug into second equation:

Expanding using the distributive property and the earlier identity mentioned to expand the binomial square:



Not the desired result.
Choice 4:


I'm going to solve the bottom equation for
since I don't want to deal with square roots.
Add 3 on both sides:

Divide both sides by 2:

Plug into equation 1:

This is not the desired result because the
variable will be squared now instead of the
variable.
Choice 5:


Solve the first equation for
by subtracting 1 on both sides:
.
Plug into equation 2:

Distribute and use the binomial square identity used earlier:



.
This is the desired result.
The angle of rotation is the minimum angle in which you rotate a regular polygon such that the figure appears unchanged. The formula for that is dividing one angle of revolution by its number of sides.
Angle of Rotation = 360°/n
Angle of Rotation = 360°/72 = 5°
Answer:
24
Step-by-step explanation: