Solve the equation x^4+7x^2-18=0 and express each solution in a+bi form

Astudent survey asked: "how tall are you (in inches)? " here's the data: 67, 72, 73, 60, 65, 86, 72, 69, 74 give the five number summary. a. median: 73, mean: 70.89, iqr: 5, min: 60, max: 74 b. 60, 66, 72, 73.5, 86 c. 60, 67, 72, 73, 74 d. 0, 60, 70, 89, 74, 100

Use stokes' theorem to evaluate c f · dr where c is oriented counterclockwise as viewed from above. f(x, y, z) = xyi + 5zj + 7yk, c is the curve of intersection of the plane x + z = 8 and the cylinder x2 + y2 = 81.

Find the area of the region between a regular hexagon with sides of 6" and its inscribed circle.