What questions can you use the quadratic formula for?

[JakePearson]

hey guys, could u use the quadratic formula;

x = -b +/- sqrt (-b² - 4ac)
2a
for the following questions;

y = 4x² - x

y = 4x² -1

y = x² + 4

and

y = -2x² + 4x

i ask this as there is no value for (c)

help me :)

 

[tiny-tim]

Hi JakePearson!

(have a square-root: √ and a ± )

Yup! You can always use that formula …

just put c = 0 (or b = 0 as the case may be) ​

 

[djeitnstine]

You need to show working before anyone can help you.

If there is no real root for an answer, usually means the answer is imaginary. As is the case for c)

 

[JakePearson]

cheers tiny-tim, thanks, ill use those :)

 

[PhanthomJay]

x = [-b +/- sqrt (+b[/color]² - 4ac)]/2a

Note correction, there's no minus sign in front of the 'b squared' term

y = 4x² - x = 0 [/color]

Note that the y value must be zero in order to use the quadratic formula