# can someone please explain.

G

#### Guest

##### Guest
Hi folks,

This is my first post so please accept my aplologies if it's not quite right.

I'm doing a basic maths course, but this one equation is driving me mad. I know the answer is 2.8 by typing it in to a equation solver, and it resolves correctly, however I just can see how it's worked out.

y=0.25t^2-2t+4 were y=0.36

If some kind person could offer some help, I'd be very grateful.

Many thanks in advance.

Alan

#### galactus

##### Super Moderator
Staff member
Subtract .36 from both sides. This gives you the quadratic:

$$\displaystyle \L\\\frac{1}{4}t^{2}-2t+\frac{91}{25}=0$$

Now solve using the quadratic formula. There will be two solutions. $$\displaystyle \L\\\frac{14}{5}$$ is just one of them.

#### TchrWill

##### Full Member
Hi folks,
This is my first post so please accept my aplologies if it's not quite right.
I'm doing a basic maths course, but this one equation is driving me mad. I know the answer is 2.8 by typing it in to a equation solver, and it resolves correctly, however I just can see how it's worked out.
y=0.25t^2-2t+4 were y=0.36
If some kind person could offer some help, I'd be very grateful.
Many thanks in advance.
Alan

For y = .36 we end up with .25t^2 - 2t + 3.64 or t^2 - 8t + 14.56.

Using the quadratic equation,
t = [8+/-sqrt(64 - 58.24)]/2
t = [8+/-sqrt(5.76)]/2
t = [8 +/-2.4]/2 = 10.46/2 = 5.2 or 5.6/2 = 2.8

G

#### Guest

##### Guest
Thanks for these folks, but can you go into a little more detail. Sorry I feel really thick, I just don't get it....

Sorry to be a bother.

Alan

#### stapel

##### Super Moderator
Staff member
amcdee said:
...can you go into a little more detail.
The tutors listed the steps to use, gave the formula to use, and then displayed the use of said formula. That is, they provided the fully-worked solution. What more "detail" were you needing?

Please be specific. Thank you.

Eliz.

G

#### Guest

##### Guest
I'm sorry I just don't understand. As I said I'm sorry to be a bother.

I thank those that have taken the trouble / time to reply. Hopefully one day it will make sense. Guess my best bet, is to talk to my tutor(s).

Eliz, I got the impress that my request for further explaination / detail, has irritate you. For that I'm sorry, I'm just trying to get my head round this and struggling.

Wishing you all, all the best.

Kindest regards,

Alan[/list][/quote]

#### stapel

##### Super Moderator
Staff member
amcdee said:
Eliz, I got the impress that my request for further explaination / detail, has irritate you.
It is to be regretted that you came to that conclusion. My post meant only what it said: with a fully-worked solution having been provided, it is difficult to see where to add any additional information. So your stating where, specifically, you were stuck would have been helpful.

I apologize for the confusion.

Eliz.

#### TchrWill

##### Full Member
i folks,
This is my first post so please accept my aplologies if it's not quite right.
I'm doing a basic maths course, but this one equation is driving me mad. I know the answer is 2.8 by typing it in to a equation solver, and it resolves correctly, however I just can see how it's worked out.
y=0.25t^2-2t+4 were y=0.36
If some kind person could offer some help, I'd be very grateful.
Many thanks in advance.
Alan

Since we have no idea as to your level of knowledge, it is hard to know at what level to provde the solutoion.

1--You were given the equation y = .25t^2 - 2t + 4 where y = .36.
2--For y = .36 we subtract .36 from both sides end up with .25t^2 - 2t + 3.64 = 0 or t^2 - 8t + 14.56 = 0, after dividing through by .25.
3--From the standard format of a quadratic equation, ax^2 + bx + c = 0, the quadratic formuls x = [-b+/-sqrt(b^2 - 4ac]/2a was derived for solving the equation.
4--Using the quadratic equation, t = [+8+/-sqrt(8^2 - 4(1)3.64)]/2
5--t = [+8+/-sqrt(8^2 - 4(1)3.64)]/2 = [8+/-sqrt(5.76)]/2
6--t = [8 +/-2.4]/2 = 10.46/2 = 5.2 or 5.6/2 = 2.8

I do hope this clears up any problems you were having understanding the solution path.