Some please solve and explain

Examine the following sets of events. set a: {1, 5, 7, 9, 14} set b: {2, 5, 6, 8, 14, 17} which of the following represents the intersection of set a and set b ? {∅} {5, 14} {1, 2, 5, 6, 7, 8, 9, 14, 17} {1, 2, 6, 7, 8, 9, 17}

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?

Adecibel is a logarithmic unit that can be used to measure the intensity of a sound. the function y = 10logx gives the intensity of a sound in decibels, where x is the ratio of the intensity of the sound to a reference intensity. the reference intensity is generally set at the threshold of hearing. use the graphing utility to graph the decibel function.a whisper has a sound intensity of 30 decibels. use your graph to you complete the following statement. the sound intensity of a whisper is times the reference intensity.