Question

(4+5i)(5+i) multiply

Answer 1

Are the i's imaginary numbers or just regular i's?

Answer 2

Use the FOIL method- multiply the first 2 terms, then the outer two, then inner two, and then the last ones. Remember that if you have an i^2, it's a -1.

Ex:
(a+b)(c+d)
ac+ad+cb+bd

Answer 3

NOTE: i^2=-1
(4+5i)(5+i)
(4*5i)+(4*5)+(5i*5)+(5i*i)
20i+20+25i+5i^2
20+45i+5i^2
and i^2=-1
so 20+45i+5*(-1)
45i+20-5
45i+15 should be your answer