Which two answers are correct?

Question

Answer

Zero
padding reduces aliasing in the spectrum.

Answer

A
butterfly requires 4 real-valued multiplications and 6 real-valued additions.

Answer

The
number of butterflies per stage of an N-point radix-2 FFT is log2(N).

Answer

The
Discrete-Time Fourier Transform (DTFT) has a periodic discrete spectrum.

Answer

Spectral
resolution is increased when using a window other than a rectangular one.

Answer

A
Blackman window has a wider main lobe than the rectangular window of same
length.

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