8 - 2 (4 + 2^2) i put my answer as 48 but the teacher says its wrong? please explain

In simplified exponential notation, the expression a^2•a^-3•a 1/a 0

Which of the following represents a number squared is equal to twenty more than nine times that number ? a) x squared = 9x + 20 b) x squared = 20x + 9 c) x squared > 9 + 20x d) x squared = 9 + x + 20

What is the arc length when θ =pi over 3 and the radius is 5 cm? (5 points) 5 pi over 3 cm 10 pi over 3 cm 16 pi over 3 cm pi over 3 cm