## Quadratic formula help for 0.2xsquared + 4.5x - 2.8 = 0

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.
qsamuels01
Posts: 1
Joined: Wed Feb 25, 2009 2:54 am
Contact:

### Quadratic formula help for 0.2xsquared + 4.5x - 2.8 = 0

More than stumped with this problem.

0.2xsquared + 4.5x - 2.8 = 0

man i would be awsome if some one helped me with this.

DAiv
Posts: 35
Joined: Tue Dec 16, 2008 7:47 pm
Contact:

### Re: Quadratic formula help.

Hi, welcome to the forums.

The Quadratic Forumula section explains how to solve awkward-looking quadratics.

For $\, 0.2x^2 \,+\, 4.5x \,-\, 2.8$, a = 0.2, b = 4.5, and c = -2.8 (note the minus sign).

Just plug the values into the quadratic formula and away you go.

If you get stuck, post your working out up to that point so we can see where you're having difficulties.

DAiv

stapel_eliz
Posts: 1628
Joined: Mon Dec 08, 2008 4:22 pm
Contact:
qsamuels01 wrote:0.2xsquared + 4.5x - 2.8 = 0

As ably explained in the previous reply (thank you, DAiv!), the Quadratic Formula works in exactly the same way, regardless of the form of the coefficients (whole numbers, fractions, or decimals). But if you're bogging down with the decimals, get rid of them!

Since this is an equation, you can multiply through or divide through by whatever you like, and you'll still end up with the same solution values. If you don't like tenths, multiply through by 10 to "clear" them:

. . . . .$10\left(0.2x^2\, +\, 4.5x\, -\, 2.8\right)\, =\, 10(0)$

. . . . .$10\left(0.2\right)x^2\, +\, 10\left(4.5\right)x\, -\, 10\left(2.8\right)\, =\, 10(0)$

. . . . .$2x^2\, +\, 45x\, -\, 28\, =\, 0$

Then plug-n-chug in the usual way:

. . . . .$x\, =\, \frac{-(45)\, \pm\, \sqrt{(45)^2\, -\, 4(2)(-28)}}{2(2)}$

...and so forth.

If you get stuck, please reply showing how far you have gotten. Thank you!

Return to “Intermediate Algebra”