Answer:
(6 + i)(2 + 9i) = 3 + 56i
Step-by-step explanation:
Use FOIL: (a + b)(c + d) = ac + ad + bc + bd
and i² = -1
(6 + i)(2 + 9i) = (6)(2) + (6)(9i) + (i)(2) + (i)(9i)
= 12 + 54i + 2i + 9i²
= 12 + 54i + 2i + 9(-1)
= 12 + 54i + 2i - 9 combine like terms
= (12 - 9) + (54i + 2i)
= 3 + 56i
