Answer: u = -4w + 9
<u>Step-by-step explanation:</u>
u - 5 = -4(w - 1)
u - 5 = -4w + 4
<u> +5 </u> <u> +5 </u>
u = -4w + 9
Answer:
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.
