1. Let's state the problem: You are solving a system of equations involving currents $I_1$, $I_2$, and $I_3$ using the form $a_1x + b_1y + c_1 + d_1 = 0$ and obtained some currents with negative signs while others positive. 2. The negative sign in current values indicates direction according to your sign convention. A negative value means the actual current direction is opposite to the one assumed in your initial setup. 3. When you rewrite equations as $a_1x+b_1y+c_1+d_1=0$, each coefficient and constant carries directional meaning based on chosen reference directions. If initial assumptions about current directions differ, signs in solutions can differ. 4. To fix sign issues, check and verify the direction assumptions for each current in the circuit. Make sure the direction in your equations matches the physical circuit or clearly mark your assumed directions. 5. Negative signs are not errors; they reflect opposite directions. If you want all positive, redefine the current directions or interpret negative values accordingly. 6. For example, if $I_1 = -5$, it means the true $I_1$ flow is opposite to the assumed. 7. Summary: Incorrect signs come from initial direction assumptions, not calculation mistakes. To fix, align your directions or interpret signs as flow directions.