What is the radius of this circle?

What is the standard form of -5x^2+2x^4-11+x^3+3x

Acircle has a circumference of 28.36 units what is the diameter of the circle

Which values of p and q result in an equation with exactly one solution? px-43=-42x+q choose all answers that apply: a) p=-43 and q=-43 b) p=42 and q=43 c) p=43 and q=−42 d) p=42 and q=42