Simplify the expression.
(-5i)(-3i)
a.15i
b.-15i
c.-15
d.15
Of course you have to know that i^2 = -1
so (-5i)(-3i)
= 15i^2
= 15(-1)
= -15
d. 15
To simplify the expression (-5i)(-3i), we can use the fact that i^2 = -1.
Multiplying the terms together, we get:
(-5i)(-3i) = -5(-3)i*i
Since i^2 = -1, we have:
-5(-3)i*i = 15i^2
Substituting -1 for i^2, we have:
15i^2 = 15(-1) = -15
Therefore, the simplified expression is -15.
So the correct answer is c. -15.
To simplify the expression (-5i)(-3i), we need to multiply the two imaginary numbers together. Let's break it down step by step:
(-5i)(-3i) can also be written as (-5)(i)(-3)(i).
First, we multiply the real numbers (-5)(-3) = 15.
Next, we multiply the imaginary units (i)(i) = i^2. Remember that i^2 is defined as -1.
So, (-5i)(-3i) simplifies to 15(i^2).
Since i^2 is -1, we can substitute -1 in the expression: 15(i^2) = 15(-1).
Finally, multiplying 15 by -1 gives us -15.
Therefore, the simplified expression (-5i)(-3i) is equal to -15.
Thus, the correct option is c. -15.