Post by: Mulan on May 09, 2010, 08:15:21 pm
Post by: Mao on May 09, 2010, 08:17:27 pm
A^2 - 5A + 4 = 0
use quadratic formula. :)
Post by: Mulan on May 09, 2010, 08:21:50 pm
Let A = 5^x
A^2 - 5A + 5 = 0
use quadratic formula. :)
thats what I did but i got the wrong answer D:
the answers x = 0.86, 0 but i got x = 1,4
i just factorised it to find x, not the quadratic formula. is that wrong?
Post by: Mao on May 09, 2010, 08:26:57 pm
Post by: Mulan on May 09, 2010, 08:32:14 pm
You are almost there,omg yea! woopsies., thus solve
and
i forgot that I made 5^x=Y
thanks so much :)
Post by: Mulan on May 10, 2010, 09:47:56 pm
solve 5(3^x) - 40 (3^-x)=17 for x
Post by: kamil9876 on May 10, 2010, 09:50:40 pm
Post by: Mulan on May 10, 2010, 09:57:17 pm
multiply both sides byy do you multiply both sides by 3^x?, notice that you get a quadratic similair to the one before.
Post by: m@tty on May 10, 2010, 10:06:40 pm
you get a quadratic similair to the one before.
It is much easier to solve.
Then solve as a quadratic in
Post by: Mulan on May 10, 2010, 10:12:42 pm
So thatyou get a quadratic similair to the one before.
It is much easier to solve.. where
(which holds for all real numbers.)
Then solve as a quadratic in
ohhhh thanks you guys :) really helped a lot