Hint: The cube roots of unity can be defined as the numbers which when raised to the power of 3 gives the result as 1 i.e., in simple words, the cube root of unity is the cube root of 1 i.e., 3√1. To show that (2−w)(2−w2)(2−w10)(2−w11)=49 hence, consider the properties of the cube root to obtain the given equation
Step-by-step explanation:
Correct option is
D
−128ω
2
Since w is the imaginary cube root of unity
w
3
=1 and
1+w+w
2
=0 …(i)
Hence
(1+w−w
2
)
7
=((1+w)−w
2
)
7
=(−w
2
−w
2
)
7
…from i
=(−2w
2
)
7
=−128w
14
=−128w
12
.w
2
=−128(w
3
)
4
.w
2
=−128w
2
…since w
3
=1.
Answer:
Hint: The cube roots of unity can be defined as the numbers which when raised to the power of 3 gives the result as 1 i.e., in simple words, the cube root of unity is the cube root of 1 i.e., 3√1. To show that (2−w)(2−w2)(2−w10)(2−w11)=49 hence, consider the properties of the cube root to obtain the given equation