00:01
So it seems like you know kind of the first thing to do.
00:03
So you have this 15t over t squared plus 9.
00:08
And i'll just kind of reiterate that first one.
00:10
You should have plugged in 5 in for your t's.
00:13
And had you done that, what i notice is i got 75 on top, 15 times 5, and then 34 on bottom, because it's 25, 25 plus 9.
00:27
And when you divide, you do get that same approximate answer, 2 .2, 0, 5, 8, 8.
00:36
But it looks like you are marked correct for saying 2 .2.
00:40
So in the next one, when do we get 1 mg? well, what i would do for letter b is take the equation and set it equal to 1.
00:54
And so what you have to do here is multiply the t squared plus 9 to the right side.
01:00
And at this point, i would use a quadratic.
01:05
No matter what times anything, it's just that thing.
01:07
So t squared minus 15t plus 9, but that's not factorable.
01:13
So you have to do the quadratic formula t equals negative b plus or minus the square root of b squared.
01:19
So negative 15 squared is 225 minus 4 times a times c all over 2a.
01:27
And i'm just going to type that into my calculator.
01:30
So 15 plus the square root of 225 minus 36 over 2.
01:36
So i get one answer of 14 .37.
01:39
But it looks like rounding to one decimal is ok.
01:42
And let me see what happens if i do the minus.
01:46
Minus actually gives me another answer that's actually just a little bit smaller.
01:51
So let me just write equals in front 0 .6 with a comma...