Explain why x squared -8x+20 is always positive

Sienna planned a trapezoid-shaped garden, as shown in the drawing below. she decides to change the length of the top of the trapezoid-shaped garden from 32 ft to 24 ft. which expression finds the change in the scale factor?

1. there are 25 students who started computer programming in elementary school and 25 students who started computer programming in middle school. the first group had a mean final project grade of 95% and the second group had a mean final project grade of 92%. the line plot shows the differences after 10 rerandomizations. determine whether the difference in the means of the two groups is significant based on the line plot. explain your answer.

Need on this geometry question. explain how you did it.