Answer:
c ≈ 0.00782852
, 3.99906481
Step-by-step explanation:
Answer:
<u>It</u><u> </u><u>is</u><u> </u>
<u>
</u>
Step-by-step explanation:

Answer:
170
Step-by-step explanation:
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.
You would isolate the variable for ex
2x+3=9
2x=9-3
2x=6
x=3