Write the equation of a circle with a center (-9,0) and radius 2√5

( x + 9)² + y² = 20

Step-by-step explanation:

The standard equation of a circle is ( x – h)² + ( y - k)² = r², where the center is (h, k) and r is the radius. By plugging in the given numbers from the question, we have [ x – (-9)]² + ( y - 0)² = (2√5)².

( x + 9)² +  y² = (2)(√5)(2)(√5)

(2)(2) = 4      (√5)(√5) = 5      (4)(5) = 20

( x + 9)² + y² = 20

b) the dogs need to shift their focus to human scent.