You have made an error in your substitution in the first problem. Your first term should be . Do you see why?
2^{2x+1} - 5 * 2^{x} - 12 = 0
If 2^{x} is y, then it would be like this:
y^{2} - 5y - 12 = 0
Seems simple enough, but:
equals:
And there is no string square root of 73. Is there a way to get around this, some trick perhaps?
Next one is:
I believe I have to solve the part first, and so I tried, but encountered the same problem as above: The square root ends up like a decimal - which shouldn't happen :/
And neither last nor least, is:
I don't even know how to start this one. I believe that's about it from exponentials, but I have to cover two more topics about trigonometry :O
Thanks