## anonymous 4 years ago Solve this equation. http://d.pr/i/7RDw (please show your working)

1. anonymous

2. anonymous

apply log ...

3. .Sam.

$e^{9a} + 2e^{3a} - 3e^{a} = 300$ Let $$e^a=y$$ $y^9+2y^3-3y=300$ $y^9=300+3y-2y^3$ $ln(y)^9=ln(300+3y-2y^3)$ $9ln(y)=ln(300+3y-2y^3)$ $ln(y)=\frac{1}{9}ln(300+3y-2y^3)$ $ln(e^a)=\frac{1}{9}ln(300+3e^a-2e^{3a})$ $a=\frac{1}{9}\ln(300+3e^a-2e^{3a})$

4. .Sam.

This is the proving solution, I don't think you can solve for 'a' all at one side.

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