Discover Questions

Alpha radiation is an ejected helium nucleus.Why is alpha radiation harmful yet I can breath in helium to talk funny? I have a space that is 72"x 16", how many 12"x12'tiles will i need? Urgent geometry help? Mary has x dollars. How many cents are there in x dollars?
She also has y twenty five-cent pieces. How much money does she have altogether? How to solve dy/dx = (y/x) - (y/x)^2?