Using the distance formulas, find the equation of a parabola with a focus of (3, 4) and a directrix of y = −2.

hey can someone fully explain this concept to me, i have the answer but i dont understand all the steps being taken

Suppose a laboratory has a 30 g sample of polonium-210. the half-life of polonium-210 is about 138 days how many half-lives of polonium-210 occur in 1104 days? how much polonium is in the sample 1104 days later? 9; 0.06 g 8; 0.12 g 8; 2,070 g