$ [12] Let form] = . {a} Evaluate f{4,2} and .f[3.8.2.1} and calculate at {b} Use total differential dz to approximate $3. [13] Use total dierential to approximate 1.,\"312 4.8. 1 l l [14] The total resistance R of two resistors connected in parallel circuit is given by R F R 1 2 {a} Approximate the change in R as R1 is decreased from 12 ohms to 11 ohms and R2 is increased from 10 ohms to 11 ohms. [b] Compute the actual change and compare it to the answer from the part {a}