Mathematics Grade 11 15 min

Solve a quadratic equation using the quadratic formula

Solve a quadratic equation using the quadratic formula

Tutorial Preview

1

Introduction & Learning Objectives

Learning Objectives Identify the coefficients a, b, and c from a quadratic equation in standard form. State the quadratic formula from memory. Calculate the discriminant to determine the number and type of roots (real or complex). Correctly substitute coefficients into the quadratic formula to solve for the roots. Simplify expressions involving radicals and fractions to find exact solutions. Solve quadratic equations that have two real, one real, or two complex solutions. Ever wondered how to calculate the exact trajectory of a basketball for a perfect shot? 🏀 The quadratic formula is the universal tool that makes it possible! In this tutorial, you will learn how to use the quadratic formula, a powerful and reliable method for solving any quadratic equation. Unlike factori...
2

Key Concepts & Vocabulary

TermDefinitionExample Quadratic Equation in Standard FormAn equation that can be written in the form ax² + bx + c = 0, where a, b, and c are real numbers and 'a' is not equal to zero.The equation 5x² - 2x + 7 = 0 is in standard form. CoefficientsThe numerical constants a, b, and c in the standard form of a quadratic equation.In the equation 3x² - x + 9 = 0, the coefficients are a = 3, b = -1, and c = 9. Roots (or Solutions)The values of the variable (x) that make the quadratic equation true. These are the points where the corresponding parabola intersects the x-axis.For the equation x² - 9 = 0, the roots are x = 3 and x = -3. DiscriminantThe expression b² - 4ac, which is the part of the quadratic formula under the square root symbol. Its value determines the nature and number of...
3

Core Formulas

The Quadratic Formula x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} This formula provides the exact solution(s) for x in any quadratic equation written in the standard form ax² + bx + c = 0. It is a universal method that always works. The Discriminant and Nature of Roots D = b^2 - 4ac The value of the discriminant (D) tells you about the roots without having to solve the entire formula: 1. If D > 0, there are two distinct real roots. 2. If D = 0, there is exactly one real root (a repeated root). 3. If D < 0, there are two complex conjugate roots.

4 more steps in this tutorial

Sign up free to access the complete tutorial with worked examples and practice.

Sign Up Free to Continue

Sample Practice Questions

Challenging
For what value(s) of 'k' does the quadratic equation x² - kx + 16 = 0 have exactly one real root?
A.k = ±8
B.k = 4
C.k = ±4
D.k = 8
Challenging
For which range of values of 'k' will the equation 2x² + 4x + k = 0 have two distinct real roots?
A.k > 2
B.k < 2
C.k > 8
D.k < 8
Challenging
Find the range of values for 'k' such that the quadratic equation kx² - 3x + 1 = 0 has two complex roots.
A.k < 4/9
B.k > 4/9
C.k < 9/4
D.k > 9/4

Want to practice and check your answers?

Sign up to access all questions with instant feedback, explanations, and progress tracking.

Start Practicing Free

More from Quadratic functions

Ready to find your learning gaps?

Take a free diagnostic test and get a personalized learning plan in minutes.