Real numbers x and y satisfy the following equations: x=log10(10y−1+1)−1 and y=log10(10x+1)−1. Compute 10x−y.
A number or a short expression. Spacing and $ signs are ignored.
Solution
Taking 10 to the power of both sides in each equation, these equations become: 10x=(10y−1+1)⋅10−1 and 10y=(10x+1)⋅10−1. Let a=10x and b=10y. Our equations become: 10a=b/10+1 and 10b=a+1 and we are asked to compute a/b. Subtracting the equations gives 10a−10b=b/10−a⟹11a=101b/10 giving an answer of 101/110.
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