Solution:
Given the expression:
[tex](12-6i)(3-10i)[/tex]To simplify in the form:
[tex]a+bi[/tex]step 1:
Multiply the terms in the second parenthesis by each term in the first parenthesis.
Thus,
[tex]\begin{gathered} 12(3-10i)-6i(3-10i) \\ \Rightarrow36-120i-18i+60i^2 \end{gathered}[/tex]step 2:
Collect like terms.
[tex]\begin{gathered} 36-120i-18i+60i^2 \\ \text{but } \\ i^2=-1 \\ \text{thus,} \\ 36+60(-1)-120i-18i \\ \Rightarrow36-60-120i-18i \\ =-24-138i \\ \Rightarrow-24+(-138)i \end{gathered}[/tex]Hence, the expression is simplified as
[tex]-24+(-138)i[/tex]