Which of the following equations cannot be solved using real numbers?
x-4 = 0
x+4 =0
x²-4=0
x²+4=0

The number of hours per week that the television is turned on is determined for each family in a sample. the mean of the data is 37 hours and the median is 33.2 hours. twenty-four of the families in the sample turned on the television for 22 hours or less for the week. the 13th percentile of the data is 22 hours. approximately how many families are in the sample? round your answer to the nearest integer.

The volume of a sphere is increased by 6%. calculate the corresponding percentage increased in it area.

Find the center and the radius of the circle with the equation: x^2-2x+y^2+4y+1=0?