I've tried for the last hour and a half, but I can't figure out how to solve this problem. I'd really appreciate some help.

$$\frac{50\cdot 2^x}{1+2^{-x}} = 4$$

  • $\begingroup$ The first thing I would do is let y= 2^x so the equation become 50y/(1+ y)= 4. Now multiply both sides by 1+ y. Can you solve 50y= 4(1+ y). Can you solve that for y? Once you have 2^x= y, taking logarithms of both sides xlog(2)= log(y). $\endgroup$
    – user247327
    Apr 28, 2017 at 16:39
  • $\begingroup$ @user247327 The resulting equation would be $50y/(1+1/y)=4$ $\endgroup$
    – Χpẘ
    Apr 28, 2017 at 18:08

1 Answer 1



$$\frac{50(2^x)}{1+2^{-x}} = 4$$

Let $y = 2^x$

$$50y= 4(1+y^{-1})$$

Multiply $y$ throughout and you should get a quadratic eqution.

After you solve for $y$ then solve for $x$.


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