eltexmexalexowc3yx eltexmexalexowc3yx
  • 15-09-2017
  • Mathematics
contestada

(x+9)^2 = -64 ? How to solve this ?

Respuesta :

zhrjuke
zhrjuke zhrjuke
  • 17-09-2017
x=-9+8i,-9-8i or no solution (i see someone already answered this but this is here just in case)
Answer Link
temp102 temp102
  • 18-09-2017
to solve it, remember that

for [tex]a^2=b[/tex], assume a=b and a=-b

also, [tex]i^2=-2[/tex]

so

[tex](x+9)^2=-64[/tex]
64 is a perfect square but -64 isn't
hmm, we can factor out the -1
[tex](x+9)^2=(-1)(64)[/tex[
[tex]-1=i^2[/tex]
[tex](x+9)^2=(i^2)(8^2)[/tex]
[tex](x+9)^2=(8i)^2[/tex]
square root both sides
x+9=8i or -8i
minus 9 from both sides
x=8i-9 or -8i-9
Answer Link

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