Question

How do you simplify `(-10i)(-9i)-(8i)(6+9i)`?

Answer 1

`(-10i)xx(-9i)-8i(6+9i)=-18-48i`

Explanation:

`(-10i)xx(-9i)-8i(6+9i)= (-9xx-10)i^2-48i-72i^2`

And so, `(-9xx-10)i^2-48i-72i^2`

`=` `18i^2-48i`

Of course, we know that `i^2=-1`

Thus, `18i^2-48i`

`=` `-18-48i`