Round to the nearest hundred thousand 111022

Question and answers are in the attached picture. you so much in advance.

Write a polynomial function f of least degree that has rational coefficients, a leading coefficient of 1, and the given zeros. 3, 4+2i, 1+(sqrt)7 the answer is supposed to be: f(x)=x(^5)-13x(^4)+60x(^3)-82x(^2)-144x+360 what am i doing wrong?

Which type of graph would allow us to quickly see how many students between 100 and 200 students were treated?