The easiest way is to try the point (-4,1), that is, x=-4, y=1,
to see which equation works.
b works.
The usual way to do it is to find the equation of the circle
standard form of a circle is (x-h)²+(y-k)²=r², (h,k) are the coordinates of the center, r is the radius.
in this case, the center is (-2,1), so (x+2)²+(y-1)²=r²
the given point (-4,1) is for you to find r: (-4+2)²+(1-1)²=r², r=2
so the equation is (x+2)²+(y-1)²=2²
expand it: x²+4x+4+y²-2y+1=4
x²+y²+4x-2y+1=0, which is answer b.
did you find the answers :( ??
Answer:
P(a junior or a senior)=1
Step-by-step explanation:
The formula of the probability is given by:

Where P(A) is the probability of occurring an event A, n(A) is the number of favorable outcomes and N is the total number of outcomes.
In this case, N is the total number of the students of statistics class.
N=18+10=28
The probability of the union of two mutually exclusive events is given by:

Therefore:
P(a junior or a senior) =P(a junior)+P(a senior)
Because a student is a junior or a senior, not both.
n(a junior)=18
n(a senior)=10
P(a junior)=18/28
P(a senior) = 10/28
P(a junior or a senior) = 18/28 + 10/28
Solving the sum of the fractions:
P(a junior or a senior) = 28/28 = 1