Maths Olympiad Prep

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Algebra Difficulty 4.5 AIME Find the answer

Find all possible values of da\frac{d}{a} where a26ad+8d2=0,a0a^{2}-6 a d+8 d^{2}=0, a \neq 0.

A number or a short expression. Spacing and $ signs are ignored.

Solution

Dividing a26ad+8d2=0a^{2}-6 a d+8 d^{2}=0 by a2a^{2}, we get 16da+8(da)2=01-6 \frac{d}{a}+8\left(\frac{d}{a}\right)^{2}=0. The roots of this quadratic are 12,14\frac{1}{2}, \frac{1}{4}.

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