Math Is Fun Forum

Chewy

Member

Registered: 2008-08-07

Posts: 67

So stuck

Well I am just plain stuck on this equation, I need to find x and I just can't do it. So I am turning to all of you instead.
What is the solution for x ?

Thanks in advance !

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: So stuck

First, notice that

.

So you have a (slightly) simpler equation

Multiply both sides by

:

Now expand the brackets, and simplify. This will give you a quadratic equation in x, which you should be able to solve.

Chewy

Member

Registered: 2008-08-07

Posts: 67

Re: So stuck

Thank you JaneFairfax, but I am still having trouble. I do understand how you got to this point. I am usually not having problems of this magnitude with my fundamental skills, but I still can't seem to pick it up from here, either. Please continue to be patient with me...

Am I on the right track ?

Last edited by Chewy (2008-08-10 06:20:29)

Chewy

Member

Registered: 2008-08-07

Posts: 67

Re: So stuck

Then, is it:

then plug it into the quadratic formula?

Last edited by Chewy (2008-08-10 06:25:10)

Daniel123

Member

Registered: 2007-05-23

Posts: 663

Re: So stuck

Then, is it:

then plug it into the quadratic formula?

This can be factorised.

(although I haven't looked at the previous posts)

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: So stuck

You're almost there, it should be 9x² + 16x - 25 = 0.
Changing the sign of the x coefficient never affects its factorisability though, so you'll still get a nice answer.

---

Why did the vector cross the road?
It wanted to be normal.

Chewy

Member

Registered: 2008-08-07

Posts: 67

Re: So stuck

Yes, Mathysperson, you are correct ! My mistake, and thank you for pointing that out. So now I have:

If

then

 

And if

then

Is my solution set for x :

and

  ?

Last edited by Chewy (2008-08-10 12:37:12)

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: So stuck

Looks perfect to me.

---

Why did the vector cross the road?
It wanted to be normal.

Chewy

Member

Registered: 2008-08-07

Posts: 67

Re: So stuck

Thank you Jane, Mathsyperson, and Daniel for your responses. That one was just bugging me. I got that wrong on a test a couple semesters ago, and as I looked over notes, I wanted to know the answer to that one, and how to find it. I didn't ask this of the instructor at that time, so thanks once again everyone !

Last edited by Chewy (2008-08-11 09:05:05)