What type of material are magnets usually made of​

They come from metal elements or alloys.

Explanation:

Different materials produce magnets of varying strengths. Ceramic magnets, also known as ferric magnets, are made of iron oxide in a ceramic composite. Samarium cobalt magnets are created from the combination of cobalt and samarium, which is a rare-earth element. Neodymium magnets contain boron, iron and neodymium, also a rare-earth element. The strongest naturally occurring magnet is lodestone, a form of magnetite. It attracts even small objects, such as staples and paper clips.

answer: at 24 february, 2014 the population gets twice of its initial population.

explanation:

since we have given that

the population for alpha city, t years after january 1, 2004 is given as

first we find out the initial population, i.e. t=0,

so, our quadratic equation becomes,

according to question, we have said that if the population has twice its initial population, then it becomes

so, time taken to reach this above mentioned population is given by

now, we know that time can't be negative so, we take t=9.149 years.

hence, at 24 february, 2014 the population gets twice of its initial population.