Mathematics 9709 · AS & A Level · Logarithmic and exponential functions

Logarithmic and exponential functions — practice question

By making the substitution $u = e^x$, or by another method,
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Find the solution of $e^x = 1 + 6e^{-x}$, and give your answer correct to 3 significant figures.

Worked solution & mark scheme

This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: Rewrite it as $e^{2x}-e^x-6=0$ or $u^2-u-6=0$, or an equivalent form

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