the Doppler effect
it is the change in frequency or wavelength of a wave for an observer moving relative to its source
Answer:
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Explanation:
Answer:
You may divide by a variable. But only if you know the variable is non-zero. So, if setting the variable to zero makes both sides of the equation zero, we have a solution that that variable is 0, or the equation with the variable divided out holds. E.g. solve x(x-1) = 0. you wecomle thank me later
Answer: They waited all day and didn't catch any fish.
