Please help, solve for x

The highest point on earth is the peak of mount everest if you climb to the top you would be approximately 29,035 feet above sea level at remembering that amount is 5280 feet percentage of the height of the mountain would you have to climb to reach a point 2 miles above sea level

Find the roots of the equation below. x^2 - 6 + 9 = 0

Determine which expressions represent real numbers and which expressions represent complex number. asaaap! plis!