Why does it make sense that the slopes of perpendicular lines have opposite signs?

Bob’s bank charges him a $3.15 service fee every time he uses an out-of-network atm. if bob uses an out-of-network atm an average of three times every two weeks, how much will he pay in service fees over the course of a year? a. $327.60 b. $109.20 c. $491.40 d. $245.70 select the best answer from the choices provided a b c d

Which statement about the relative areas of δabc and δxyz is true? the area of δabc > the area of δxyz the area of δabc < the area of δxyz the area of δabc = the area of δxyz more information is needed to compare.

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)