In the circuit below, the current $(l_1)$ is going into the node $($located near $R_1),$ current $(I_2)$ is going out the node $($located near $R_2$dots in the middle$),$ and current $(l_3)$ is coming out of the node $($located near $R_3$dots on the right side$).$ The loop is going from positive to negative in the left side and negative to positive on the right side.

YOU DO NOT NEED THE NUMBERS... SO IGNORE THEM

a$)$ Using the matrix technique SHOWN IN CLASS & the PRACTICE HOMEWORK...

$$Find the determinate for the entire circuit

$$ SET$-$UP THE MATRIX FIRST

$?$ Now solve it for the Determinate $[$demominator$]$

b$)$ Find $I_1$ ONLY

$(3)$ You do not need to solve for $I_2$ nor $I_3$

$(3)$ Set$-$up the matrix for this answer

$3$ Solve it for the numerator $[$top part of the $I_1$ ratio$]$

$$