4. Consider the circuit below, (a) Use the loop-current method to obtain a set of three linearly independent equations, in terms of the loop currents I1?,I2? and I3?, and the sources Vs? and Is?, but no other variables, that can be used to determine the loop currents. Simplify your equations and write them with integer-valued coefficients. (b) Use the node-voltage method to obtain a set of three linearly independent equations, in terms of the node voltages V1?,V2? and V3?, and the sources Vs? and Is?, but no other variables, that can be used to determine the node voltages. Simplify your equations and write them with integer-valued coefficients. (c) Is it known that V3?=k1?Vs?+k2?Is?. Use superposition to determine the values of k1? and k2?. (d) Assuming that Vs?=10 V and Is?=1 A, use your equations from part (a) to obtain the loop currents I1?,I2? and I3?. It is fine to use calculators, software, or python to solve this problem but keep in mind that you might need to do it in an exam.