a student has simplified the following expression incorrectly

identify the mistake that was made and simply the ex;ression correctly show all necessary steps
(-3i)(-5i)
15i was the studentts answer

1 answer

The mistake made by the student is in the distribution of the negative signs. To simplify the expression correctly, we use the property that i^2 is equal to -1.

(-3i)(-5i)
= -3(-5) * i * i
= 15 * i^2
= 15 * (-1) [Substituting i^2 with -1]
= -15

So, the correct simplification of the expression is -15.