For i = -1, what is the value of a when (3 + 6i) + (-5 + 17i) is written in a + bi form?
A. -2
B. 2
C. 8
D. 23

Mount saint helen the great lakes and death valley are physical features of the earth which scientific term describes these features

Earth's atmosphere is unique among the planets and is able to support life because it contains a large amount of a) oxygen b) helium c) methane d) carbon dioxide

The ancestors of horses possessed feet with five digits. over time, with the development of grasslands, the digits fused and formed hooves. what evolutionary advantage did this transformation serve? a. it allowed them to climb rocky surfaces with ease. b. it allowed them to graze better. c. it enabled them to run faster from predators. d. it let them see clearly through the grasslands. e. it made them taller.