without-using-a-substitution-for-3-x-solve-the-equation-9-x-3-x-2-36-0-

Question Number 111583 by Rio Michael last updated on 04/Sep/20

without using a substitution for 3^{x} solve the equation

9^{x} - 3^{x + 2} - 36 = 0

Answered by bemath last updated on 04/Sep/20

9^{x} - 9 . 3^{x} - 36 = 0

3^{x} = \frac{9 + \sqrt{81 + 144}}{2} = \frac{9 + 15}{2} = 12

x = \log_{3} (12) = 1 + 2 \log_{3} (2)

Commented by Rio Michael last updated on 04/Sep/20

thanks, but anyother method sir ?