Professor Curie is using the radioactive isotope Francium-223 in her research. This isotope has a half-life of 22 minutes, which means that every 22 minutes the sample has half the radioactivity it did in the previous interval. If Professor Curie has 15 grams of Francium-223, which explicit formula describes how the isotope decays? A. an=22(0.5)^15-1
B. an=22(0.5)^n-1
C. an=15(0.5)^n-1
D. an=15(22)^n-1

Hurry and answer this! circle x with a radius of 6 units and circle y with a radius of 2 units are shown which steps would prove the circles similar? translate the circles so they share a common center point, and dilate circle y by a scale factor of 4. translate the circles so the center of one circle rests on the edge of the other circle, and dilate circle y by a scale factor of 4. translate the circles so they share a common center point, and dilate circle y by a scale factor of 3. translate the circles so the center of one circle rests on the edge of the other circle, and dilate circle y by a scale factor of 3

1mile equals approximately 1.6 kilometers. which best approximates the number of miles in 6 kilometers?

Rewrite the following quadratic functions in intercept or factored form. show your work. y = 4x^2 - 19x- 5