Last week I wrote a test on exponential equations and I came across this problem;
But I could not found a way to solve it, because it has different bases, which I cannot make the same. Here is what I came up with:
Here I only have 2 bases. I tried to solve it with two changes:
And then I got this equation $$10a^2-21ab=10b^2$$
That is the furthest I managed to come. Of course I do not know if this is even correct.
Also I have seen on the internet such methods as using logarithms, but we have not taken this course yet, so it is not a solution I am looking for.