Math Help - Hii... problem with some quadratics excersises.. Can someone help me?? :D

1. Hii... problem with some quadratics excersises.. Can someone help me?? :D

Hii... I need help with some of this excersises...

1) Solve 3x2^ + 4x = 2
2) Solve x^2 + 9x + 9 = 0
3) Solve 2x^2 = 14x + 20

butt the answer cannot be like x= something and x= something else... it must be like ... or i don't know... Please help because I don't know how to do that.. thanks...!

2. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

Originally Posted by raimel
Hii... I need help with some of this excersises...

1) Solve 3x2^ + 4x = 2
2) Solve x^2 + 9x + 9 = 0
3) Solve 2x^2 = 14x + 20

butt the answer cannot be like x= something and x= something else... it must be like ... or i don't know... Please help because I don't know how to do that.. thanks...!
1. Re-write the equations to the form

$ax^2+bx+c = 0$

2. Then use the quadratic formula:

$x = \dfrac{-b \pm \sqrt{b^2-4ac}}{2a}$

3. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

Yeah... but how do i do that?? that's the confusing part.... Can you at least do number one... and then I'll see how to do it.. ?? please.. thanks!

4. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

For example the first one:
$3x^2+4x=2 \Leftrightarrow 3x^2+4x-2=0$

Now like earboth said you've to use the quadratic formula.

5. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

I know that part... but how do I use the formula... and how do I simplify the formula when I subst. the numbers.... I don't understand that part.. :\$

6. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

Ok, now you have to calculate:
$D=b^2-4ac$
In this case:
$D=4^2-[4\cdot3\cdot(-2)]=40$

Using the quadratic formula, you'll get two different solutions because $D>0$:
$x_1=\frac{-b+\sqrt{D}}{2a}=...$
$x_2=\frac{-b-\sqrt{D}}{2a}=...$

Can you complete? ...

7. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

I dont know hot to put the square thingy and all the other stuff in my computer... sorry man... but Im new at this... im really sorry for being dumb..

8. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

You don't have to be sorry everyone is here to learn ...

Ok, you just have to fill in:
$x_1=\frac{-4+\sqrt{40}}{6}$
$x_2=\frac{-4-\sqrt{40}}{6}$

These are the two solutions of the quadratic equation.

Try it now for the other equations ...

9. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

that would be... (-2 + 2sq.rt10) / 3??

10. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

hooo I got it now... thankkks.... but you dont symplify??? in each eq???

11. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

Almost, if you want to simplify it has to be:
$\frac{-4+\sqrt{40}}{6}=\frac{-4+\sqrt{4\cdot 10}}{6}=\frac{-2-\sqrt{10}}{3}$

Yes, to simplify is important, but I didn't do it yet so you could clearly see the solution.

Do you understand now? ...

12. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

This is exactly the same as the thread you posted yesterday. If you honestly have no idea how to solve quadratic equations and, apparently, cannot understand what people are saying here, you need to talk to your teacher about this.

13. Re: Hii... problem with some quadratics excersises.. Can someone help me?? :D

Maaan,,... thaaaaankssssss... I super got it now... wooow cool place to ask questions.. ha? Im new here, and this is my first qestion... and thanks to you... i super got it.. thankssssssss!!!!!!!