Need help with the first one(first pic)

plz. If u can help me out with the second one too plz or just tell me what to do.

Please do answer the first pic one. I really need help with that one. Do the matlab computations as well plz

4.(10 points) RI R2 V2 The electrical circuit shown consists of resistors and voltage sources. Using the mesh current method based on Kirchhoffs voltage law, the following system of equations can be obtained: Vi Rs Ri R1 14 Rewrite the system of linear equations in the format A i = b. where i is the vector consists of i, i2, i3 and i4 . Using MATLAB, show that matrix A is invertible and then solve the system to determine i. R.-12 R,-411 R,-8 Rs = 552. R.-14