If w = 1 is a cube root of unity and a + b = 1 , a 3 + b 3 = 1 0 0 1 . Find the value of ( a w 2 + b w ) ( a w + b w 2 )
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@Tanishq Varshney Thanks for the solution
Good solution,but overrated question.
( a ω 2 + b ω ) ( a ω + b ω 2 ) = a 2 + b 2 + a b ( ω + ω 2 ) = a 2 + b 2 − a b . a + b a 3 + b 3 = a 2 + b 2 − a b = 1 1 0 0 1 = 1 0 0 1 .
right man...... I also did it exactly the same way
Since w^3 = 1 and w is complex and imaginary, w^2 + w + 1 = 0.
(aw^2 + bw)(aw + bw^2) = (a^2)(w^3) + ab(w^4) + ab(w^2) + (b^2)(w^3) = (a^2 + b^2) + abw + ab(w^2) = (a^2 + b^2) + ab(w + w^2) = a^2 + b^2 - ab
From the systems for a and b, a^2 - ab + b^2 = 1001.
Hence, the answer.
y is it with 335 point (level 5)?? its a level 3 question!!!
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Yes Sir I agree you but I first set it to Level 3
Multiplying and dividing by w. We get (aw+b)(aw^2+b)= a^2+b^2+ab (w+w^2). This is same as (a+b)^2 -3ab=1-3(-1000/3)= 1001
+1!! use latex!!
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( a + b ) ( a 2 − a b + b 2 ) = 1 0 0 1 ................... ( 1 )
a 2 ω 3 + a b ( ω + ω 2 ) + b 2 ω 3
we know that ω 3 = 1 a n d 1 + ω 2 + ω = 0
expression reduces to a 2 − a b + b 2
as in 1
a + b = 1 , thus a 2 − a b + b 2 = 1 0 0 1