Math plzz

find the roots of the quadratic equation x^2 – 8x = 9 by completing the square. show your work

What is the measure of ac? 5 units 13 units 26 units 39 units

Two lines parallel to the same plane are parallel to eachother

Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.