Question

Sendo os complexos u = i - 4 e w = 3 - 4i, então 2u - w² é:A) 26iB) -1 -26iC) -1 +26iD) 1 +26iE) -i

Answer 1

$u=i-4 \iff 2u=2\cdot(i-4) \iff 2u=2i-8$

$w=3-4i \iff w^2=(3-4i)^2=9-2\cdot3\cdot4i+16i^2=9-24i-16 \iff w^2=-24i-7$

$2u-w^2=2i-8-(-24i-7)=2i+24i-8+7 \iff 2u-w^2=26i-1$

$\texttt{Alternativa C}$