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Equation Attack

Age 16 to 18
Challenge Level Yellow star
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Solve the equation $$a^x + b^x = 1$$ where $0< a, b < 1$ and $a + b < 1$, in the special cases:

(i) $a = b\quad $ (ii) $a = {1\over 2}, \ b={1\over 4}\quad $ (iii) $a = {1\over 2}, \ b={1\over 3}$ .

Although you can find exact solutions in special cases like (i) and (ii) it soon becomes apparent that generally you will need to use a numerical method for finding approximate solutions.

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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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