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If (5-3i)(x+iy)/(4-5i) = (2+i)^2-(3-4i)^2, then x=___ and y=____

User Makeworld
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1 Answer

1 vote
this looks complicated

lets simplify both sides

By multiplying top and bottom by the conjugate:-

left side = (5-3i)(x + iy) (4+5i) (5-3i)(x + iy) (4+5i)
------------------------ = ------------------------
(4-5i)(4+5i) 41

right side = (2 + i + 3-4)(2+i - 3 + 4i) (by Difference of 2 squares)

= 5-3i)(-1 + 4i)

so as left side = right side

(5-3i)(x+yi)(4+5i) = 41 (5-3i)(-1+5i)

5-3i is common so:-

(x + iy)(4+5i) = 41(-1+5i)

4x +5xi + 4yi - 5y = -41 + 205i

4x - 5y + (5x + 4y)i = -41 + 205i

EQuating coefficients we are left with the system of equations

4x - 5y = -41
5x + 4y = 205

solving this gives x = 21 and y = 25


User Cohen
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