What questions can you use the quadratic formula for?

So the equation becomes: 0 = 4x2 - xIn summary, to solve equations using the quadratic formula, the y value must be set to zero and the formula is: x = (-b +/- sqrt(b^2 - 4ac))/2a. Remember to check for imaginary solutions if the discriminant (b^2 - 4ac) is negative.
  • #1
JakePearson
52
0
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 :)
 
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  • #2
Hi JakePearson! :smile:

(have a square-root: √ and a ± :wink:)

Yup! You can always use that formula …

just put c = 0 (or b = 0 as the case may be) :biggrin:
 
  • #3
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)
 
Last edited:
  • #4
cheers tiny-tim, thanks, ill use those :)
 
  • #5
JakePearson said:
x = [-b +/- sqrt (+b2 - 4ac)]/2a
Note correction, there's no minus sign in front of the 'b squared' term
y = 4x2 - x = 0
Note that the y value must be zero in order to use the quadratic formula
 

What is the quadratic formula?

The quadratic formula is a mathematical formula used to solve quadratic equations of the form ax^2 + bx + c = 0. It is written as x = (-b ± √(b^2 - 4ac)) / 2a.

When should I use the quadratic formula?

You should use the quadratic formula when you have a quadratic equation that cannot be easily factored or solved using other methods. This could be because the equation has complex numbers, irrational numbers, or when factoring is not possible.

How do I use the quadratic formula?

To use the quadratic formula, you first need to identify the values of a, b, and c in the equation ax^2 + bx + c = 0. Then, substitute these values into the formula x = (-b ± √(b^2 - 4ac)) / 2a and solve for x using basic algebraic operations.

What are the two solutions of the quadratic formula?

The quadratic formula can give two solutions, also known as roots, for a quadratic equation. These solutions can be real or complex numbers, and they represent the x-intercepts of the parabola represented by the equation.

What happens if the discriminant is negative in the quadratic formula?

If the discriminant (b^2 - 4ac) is negative in the quadratic formula, it means that the equation has no real solutions. Instead, the solutions will be complex numbers. This indicates that the parabola does not intersect the x-axis and does not have any x-intercepts.

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