Maths problems, please help

1. Factorize y^4+y^2+1

2. There are two identical circular metal plates. A worker claims that if he melts these metal plates and recast them into a larger circular metal plates, the radius of the original metal plate is exactly half of the new one. Do you agree with him? Explain your answer briefly. (Hints: The thickness of metal plate can be ignored.)

3. Simplify 6y/(3y^2+3y)+(y-1)/2(y+1)^2-y/(6y^2-6)