Q153 · Practice questionTechnology-freeComplex familiar1 mark
QUESTION 153
The points , and represent the three roots of on the Argand plane. The point represents .
What is the exact value of ?
(A)
(B)
(C)
(D)
WORKED SOLUTION
1 markAnswer B
ANSWER
B. .
Worked solution
The monic polynomial with roots is
Substitute and take moduli:
The three distances need not be calculated separately. The roots are , and .
A ignores the imaginary component; C adds the component magnitudes rather than taking the modulus; D squares the correct result.
Equivalent mathematically justified methods accepted.
Exact answers unless a decimal accuracy is specified.
Select B.
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