Problems 4.5 and 4.7: Use the op amp equivalent circuit in Figure 4-4 for these two problems.The advice for Problem 4.45 was updated at 3:10 PM on Oct. 28, 2011.
Problem 4.45: Use the ideal op amp assumptions for this problem.Look for voltage dividers and use node-voltage analysis if needed(but avoid writing KCL at op amp output terminals).
There are no voltage dividers in the circuit! Use node-voltage analysis and write KCL at the nodes vn1 and vn2.