What two numbers multiplied together get -78 and add up to 23

How to choose the sign of the radical in the denominator of the formula for the distance from a point to a line.

The random variable x is the number of occurrences of an event over an interval of ten minutes. it can be assumed that the probability of an occurrence is the same in any two-time periods of an equal length. it is known that the mean number of occurrences in ten minutes is 5.3. the appropriate probability distribution for the random variable

65% of students in your school participate in at least one after school activity. if there are 980 students in you school, how many do not participate in an after school activity?