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# If cx - bx^3 = 0 where b and c are non-zero numbers, what is the value

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Re: If cx - bx^3 = 0 where b and c are non-zero numbers, what is the value [#permalink]
Bunuel wrote:
If cx - bx^3 = 0 where b and c are non-zero numbers, what is the value of b - c ?

(1) cx = c
(2) bx = b

Statement 1:
Always factor when we have quadratic terms. Here we treat c as a variable, so cx is quadratic and we should pull everything to the left side first.
cx - c = 0, and c*(x - 1) = 0.
Since we can confirm c is not 0, we must have (x - 1) = 0.
This gives us x = 1. Plug in to get c - b = 0, b - c = 0, sufficient.

Statement 2:
Same as above. Sufficient.

Ans: D
Re: If cx - bx^3 = 0 where b and c are non-zero numbers, what is the value [#permalink]
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