Describe in words the surface whose equation is given. φ = π/4 (select the correct answer)
1)the top half of the right circular cone with vertex at the origin and axis the positive z-axis
2)the plane perpendicular to the xz-plane passing through z = x, where x ≥ 0
3)the plane perpendicular to the xy-plane passing through y = x, where x ≥ 0
4)the base of the right circular cone with vertex at the origin and axis the positive z-axis
5)the plane perpendicular to the yz-plane passing through z = y, where y ≥ 0

Jeffery conducted a survey in his school and found that 30 of the 50 eighth grade students' favorite subject is mathematics. based on the results, jeffery concluded that out of the 200 students in his school, 120 students' favorite subject is mathematics. select the statement that is true about jeffery's conclusion. a. jeffery's conclusion is not valid because the sample was biased since only 200 students were surveyed. b. jeffery's conclusion is valid because the sample was random since all of the students were eighth grade students. c. jeffery's conclusion is valid because the sample was random. d. jeffery's conclusion is not valid because the sample was biased since all of the students were eighth grade students.

The function show two sisters' savings account and the rate at which they plan to deposit money

Rewrite the following quadratic functions in intercept or factored form. show your work. f(t) = 20t^2 + 14t - 12