## Calculus: Early Transcendentals 8th Edition

$13+18i$
Start with the given expression: $(2+5i)(4-i)$. Distribute binomials: $8+20i-2i-5i^{2}$. Substitute $i^{2}=-1$ into the expression: $8+20i-2i+5$. Combine real and imaginary terms to arrive at the answer: $13+18i$.