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Find a quadratic expression with integer coefficients whose roots are
5/2+ 3i and
5/2-3i.

User Servik
by
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1 Answer

4 votes

Answer:

4x² -20x +61

Explanation:

the quadratic equation can be written as (x-root1)(x-root2)

(x-(5/2) -3i) (x-(5/2)+3i), distribute

x² -(5/2)x +3xi -(5/2)x + 25/4 -(15/2)i -3xi +(15/2)i -9i², simplify

x² -(5/2)x -(5/2)x + 25/4 -9, use the fact that i² =(√-1)² = -1 and substitute i²

-(5/2)x -(5/2)x + 25/4 +9, combine like terms and rewrite 9 as 36/4

x² -(10/2)x +25/4 + 36/4, combine like terms and simplify

x² -5x +61/4 is the quadratic expression yet it does not have integer coefficients so multiply by 4 to have all coefficients integers

4x² -20x +61

User Stefan Rogin
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