carcass wrote:
Is \frac{x}{p} (p 2 + q 2 + r 2 ) = xp + yq + zr?
(1) q^2 = r^2
(2) yq = zr
There are too many variables here so let's focus on logic.
Is
\frac{x}{p} (p 2 + q 2 + r 2 ) = xp + yq + zr?Is
xp + \frac{x}{p}(q 2 + r 2 ) = xp + yq + zr?Is
\frac{x}{p}(q 2 + r 2 ) = yq + zr?(1)
q^2 = r^2Even if q^2 = r^2, there are lots of other variables e.g. x, y and z which can take different values to make the two sides unequal. But if q = r = 0, the two sides become equal so not sufficient alone.
(2)
yq = zrAgain, there are no constraints on x and p and they can take different values to make the two sides of the equation unequal. But if q = r = 0, the two sides become equal so not sufficient alone.
Using both together, there are still no constraints on the values x and p can take so the two sides needn't be equal. But if q = r = 0, the two sides become equal so not sufficient.
Answer (E)
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