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The discriminant of a quadratic equation is b^2-4ac.
What does the discriminant tell you about the number and type of roots?
Use the discriminant found in Part A in the Quadratic Formula.
36
2 rational roots
1/4, -1/2
In the Quadratic Formula, b^2-4ac is the discriminant.
ax^2+bx+c=0 ⇔ x=- b±sqrt(b^2-4ac)/2a
Let's first rewrite the given equation in standard form.
Having rewritten the equation, we can identify the values of a, b, and c. 8x^2=- 2x+1 ⇔ 8x^2+ 2x+( - 1)=0 Now, let's evaluate the discriminant.
Substitute values
Calculate power
Multiply
- a(- b)=a* b
Add terms
The discriminant is 36.
We want to use the discriminant of the given quadratic equation to determine the number and type of the roots. If we do not want to know the exact values of the roots, we only need to work with the discriminant. From Part A, we know that the discriminant of the given equation is 36.
We will use the Quadratic Formula to find the exact solutions of the given equation.
x=- b±sqrt(b^2-4 a c)/2 a
Recall that we have already identified the values of a, b, and c in Part A, as well as the discriminant, b^2-4ac.
The solutions for this equation are x= - 2± 616. Let's separate them into the positive and negative cases.
| x=- 2± 6/16 | |
|---|---|
| x_1=- 2+6/16 | x_2=- 2-6/16 |
| x_1=4/16 | x_2=- 8/16 |
| x_1=1/4 | x_2=-1/2 |
Using the Quadratic Formula, we found that the solutions of the given equation are x_1= 14 and x_2=- 12.