21.18 For each of the following functions on R', determine whether it is quasiconcave, quasiconvex, both, or neither: a) e'. b) In x, c) +x, d) - x, e) x* - x. f) x* + x, 8) 3x - 5x + 7x, h) sin x. 11 10 21.18 a) Both, b) both, c) both, d) neither, e) neither, f) quasiconvex, g) both, h) neither. Answers attached ,please explain with calculation how the solutions were obtained 21.18 For each of the following functions on R', determine whether it is quasiconcave, quasiconvex, both, or neither: a) e'. b) In x, c) +x, d) - x, e) x* - x. f) x* + x, 8) 3x - 5x + 7x, h) sin x. 11 10 21.18 a) Both, b) both, c) both, d) neither, e) neither, f) quasiconvex, g) both, h) neither. Answers attached ,please explain with calculation how the solutions were obtained