B would be the correct answer
If you expand out the brackets you get this,
(4+5i)(a+2i) = 4a + (5a)i + 8i - 10
The -10 comes from 5i * 2i.
Squaring i becomes -1.
Let's group the real stuff together,
and imaginary separately,
(4a - 10) + (5a + 8)i
For this to be purely imaginary,
the real part needs to be zero.
Therefore 4a - 10 = 0
Solve for a.
Answer:
I think you can
Step-by-step explanation:
Answer:
no
Step-by-step explanation:
i just know
Consider the top half of a sphere centered at the origin with radius

, which can be described by the equation

and consider a plane

with

. Call the region between the two surfaces

. The volume of

is given by the triple integral

Converting to polar coordinates will help make this computation easier. Set

Now, the volume can be computed with the integral

You should get