[Solved] The first person to use a microscope to observe cells invisible to the naked eye was: A)Robert Hooke B)Matthias Schleiden C)Anton van Leeuwenhoek D)Louis Pasteur Multiple IRRs: This occurs when a project or investment has more than one internal rate of return, typically due to multiple cash flow sign changes over the investment's lifetime. Negative Cash Flow: A situation where a business or individual's outgoing cash exceeds the incoming cash during a specific period, indicating potential financial trouble. Average Net Income: null Straight-Line Depreciation: A procedure for breaking down the cost of a tangible asset over its period of operation in equal annual installments.