What is the interquartile range of this data set? Enter your answer in the box.

A stem-and-leaf plot with a stem value of 2 with a leaf value of 0 and 5, a stem value of 3 with a leaf value of 0, 0, and 1, and a stem value of 4 with a leaf value of 0, 1, 9.
Key: 1|5 means 15

the answer would be  

a.

3: 1

step-by-step explanation:

x^2 + 81

we can factor this using difference of square binomials.

rewrite the equation:

x^2 - (-81)

factor:

(a^2 - b^2) = (√a^2 + √b^2)(√a^2 - √b^2)

(x^2 - (-81) = (x + √-81)(x - √-81)

we can remove the - from under the radical by multiplying it by i.

(x^2 - (-81) = (x + i√81)(x - i√81)

(x^2 - (-81) = (x + 9i)(x - 9i)

we can check our answer by using foil:

x^2 - 9ix + 9ix - 81i^2

x^2 - 81^2

i^2 = -1

x^2 + 81