A ladder that is 21 feet long is propped against a building. The bottom of the ladder was placed 4 feet from the base of the building. How high up on the building does the ladder reach? Round the answer to the nearest tenth of a foot.

Simplify each expression using the definition, identities, and properties of imaginary numbers. match each term in the list on the left to its equivalent simplified form on the right. 1. (i 3)2(-i 0)3(3i 2)4 -4 2. (i 3i -5)2(i 4i -3)0 1 3. (-i 4i 2)(2i)2(i -1i 5)3(i 0)-3 -i 4. i 3[(i 2i 3i 4)(i 0i 2i 5)]2 81