Question

1-Calcule e marque qual o novo complexo, após a multiplicação


2-Dado o polinômio P(x)= 2x²+X+3. Calcule o valor Para(3).

a)18
b)24
c)30
d)46
e)12​

Answer 1

1)

$(2 + 7i)(5 + 2i)\\\\\textrm{Multiplicando os termos, temos:}\\\\10 + 4i + 35i + 14i^2\\\\= 10 + 39i + 14i^2\\\\\textrm{Note que}\ i = \sqrt{-1}\ \textm{ e, portanto,}\ i^2 = -1\textrm{. Logo}\\\\10 + 39i + 14i^2\\\\= 10 + 39i - 14\\\\= \boxed{-4 + 39i}$

2)

$P(x) = 2x^2 + x + 3\\\\\textrm{Se}\ x = 3\textrm{, basta substituir}\ x\ \textrm{por}\ 3\ \textrm{na equa\c{c}\~{a}o:}\\\\P(3) = 2(3)^2 + 3 + 3\\\\P(3) = 18 + 3 + 3\\\\\boxed{P(3) = 24}$