turtlebug9399 turtlebug9399
  • 25-01-2019
  • Mathematics
contestada

how do I solve this? (6+8i)(4-7i)
step by step??
I just need a tutor...

Respuesta :

gmany
gmany gmany
  • 25-01-2019

[tex]Use:\\\\FOIL:\\(a + b)(c + d) = ac + ad + bc + bd\\\\i=\sqrt{-1}\to i^2=-1\\-----------------------\\\\(6+8i)(4-7i)=(6)(4)+(6)(-7i)+(8i)(4)+(8i)(-7i)\\\\=24-42i+32i-56i^2=24-10i-56(-1)=24-10i+56\\\\=80-10i\\\\Answer:\ \boxed{(6+8i)(4-7i)=80-10i}[/tex]

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