Cramer's Rule Calculator: Solve 2‑ and 3‑Equation Linear Systems Quickly
Cramer’s Rule & Calculator for Linear Circuit Analysis | Step by Step with Solved Examples
Today, we are going to share another simple but powerful circuit analysis technique which is known as “Cramer’s Rule“.- SUPERMESH Circuit Analysis | Step by Step with Solved Example

Cramer’s Rule Calculator for 2×2 (Two Equations System)
Example 2: Use Mesh Analysis to determine the three mesh currents in the circuit below. Use Cramer’s rule for simplification.
First of all, apply the KVL on each mesh one by one, and write its equations.
-7+1(i1–i2) +6+2(i1–i3) = 0
1(i2– i1) + 2i2 + 3(i2– i3) = 0
2(i3– i1) – 6+3(i3– i2) +1i3 = 0
Simplifying,
3i1 – i2 – 2i3 = 1 … Eq….. (1)
– i1 + 6i2 – 3i3 = 0 … Eq….. (2)
-2i1 – 3i2 + 6i3 = 6 … Eq….. (3)
Now, write the above equations in the matrix form.
3i1– i2– 2i3 = 1
–i1+ 6i2– 3i3 = 0
-2i1– 3i2+ 6i3 = 6
Now, we will find the coefficient determinant of ∆. How will we do that? Just check the fig below for better explanation.
Click image to enlarge
So the full step is shown below.
∆ = +3 (6 x 6) – (- 3 x –3) – (-1 (-1 x 6)-(-2 x –3) + (-2 (-1 x –3) – (-2 x 6)
∆ = 81 -12 -30 = 39
Now, find the ∆1 by the same way as explained above. But, just replace the first column of the matrix with the “Answer Column”. For detail, check the fig shown below.
So, here is the full step to find ∆1. Here, we replaced the “Blue Guys” in the first column with “Black Guys” :).
= +1(36-9) – (–1[0+18]) –2(0-36)
= 27 + 18 + 72
∆1 = 117
Again, find the ∆2 with the same method as explained earlier. Just replace the second column of the matrix with the “Answer column” i.e. replace the “Red guys” in the center column with “Black Guys” as shown below.
= +3 (0 +18) -1[(-6)-(+6)] –2(-6-0)
= 54+12+12 = 78
∆2 = 78
Finally, find the last ∆3. Just replace the third column with the “Answer column” i.e. replace the “Green guys in the third column with “Black guys” as shown below.
= +3 (6 x 6) – (-3 x 0) – [-1(-1 x 6) – (-2 x 0)] + [1(-1) x (-3) – (-2) x (6)]
= 108 + 6 + 15
∆3 = 117
Now, solve and find the unknown values of current, i.e. i1, i2 and i3.
As, Cramer’s rule says that, variables i.e. i1 = ∆1/∆1, i2 = ∆/∆2 and i3 = ∆/∆3.
Therefore,
i1 = ∆1/∆1
= 117/39
i1 = 3A
And i2,
i2 = = ∆/∆2
= 78/39
i2 = 2A
And finally, i3;
i3 = ∆/∆3
= 117/39
i3 = 3A.
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