Worth 75 points. Need help fast with Calculus Vectors.

Ming says that 0.24 > 1/4 because 0.24= 2/4. which best explains mings error

Find the solution(s) to x^2-14+49=0

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?