To express a complex number in the form x+yi, the denominator must be a real number.
Multiplying a complex number by its conjugate results in a real number:
(a+bi)(a−bi)=a2−(bi)2=a2−b2i2=a2+b2
In Step 1, the denominator was 2+3i. Its conjugate is 2−3i.
Multiplying the denominator by 2−3i makes it a real number:
(2+3i)(2−3i)=22+32=4+9=13
To maintain the value of the fraction, the numerator must also be multiplied by the same term, 2−3i. This is equivalent to multiplying the entire fraction by 2−3i2−3i, which is equal to 1.