Posted by Shay on .
simplify the following expressions involving complex numbers.
(3+2i)(7i)
10 + 3i
how did you do that?
can you show me this one and explain how this time?
(3+2i)(7i)
or even
(32i)^2
you would do 3+2i=5i, then 7i=7i then 5i+7i=12i
(3+2i)(7i) =
(3+2i) + (7 + i) =
3 + 7 + 2i + i =
10 + 3i
(3+2i)*(7i) =
(3+2i)*(7 + i) =
[3*7 + 3*i + 2i*7 +2i*i] =
[21 + 3i + 14i  2] =
[19 + 17i]
(32i)^2 =
9  12i  4 =
5  12 i
thankyou, you are very good at math!
can you help with this one please and thankyou?
Determine the values of k if the graph of
y=2x^2sx+3k
intersects the xaxis at 2 distinct points.
Thanks!
a x^2 + bx + c = 0 has two different roots if the discriminant D defined as:
D = b^2  4 a c does not equal zero.
If a, b and c are real numbers then for D > 0 there are two real roots while for D < 0 there are two complex roots.
In this problem we have to demand that D > 0 >
D = s^2  24 k > 0 >
k < s^2/24

can someone please help me? 
hi,
if anyone knows the answer please help me on this one too!