First find the lowest common multiple of the denominators which are 12 3 9 and 27 these all go into 108. Next divide 108 by the original denominators for example 108/12 is 9 then times 9 by the numerator which is 5 and you get 45 so the first one is 45/108. Do this for them all and order by the size of the numerator
Im not 100% about how this question is explained or written but i think its 8
Answer:
I think the answer is 12,0000
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.
