The Quadratic Formula

The Quadratic Formula

By Deb Scott

The Quadratic Formula

What Does It Do?

• solves quadratic equations

• find x-intercepts (also called zeros, solutions, and roots)

Steps

• Set the equation equal to zero

• Identify a, b, and c

• substitute into the quadratic formula

• Do the math!

Multiple Select

Choose the correct values for a, b, and c.

$$4x^2-5x\ =\ 9$$  

• a = 4

• b = 5

• c = 9

• b = -5

• c = -9

Multiple Choice

Solve using The Quadratic Formula.

$$x^2\ -\ 3x\ -\ 4\ =\ 0$$  

• x = 1, -4

• x =  $$\frac{3\pm5}{2}$$  

• x = -1, 4

• x =  $$\frac{-3\pm5}{2}$$  

Multiple Choice

Solutions of a quadratic equation are also called

• roots

• x-intercepts

• zeros

• All of the above

Multiple Choice

Identify a, b and c in the quadratic equation: $$2x^2-3x-5=0$$  

• a = 2 , b = 3, c = -5

• a = 2, b = -3, c = 5

• a = 2, b = -3, c = -5

• a = -2, b = 3, c = 5

Multiple Choice

What is the quadratic formula?

• $$x=\frac{b-\sqrt{\left(b\right)^2-4\left(a\right)\left(c\right)}}{2\left(a\right)}$$

• $$x=\frac{-\left(b\right)\pm\sqrt{\left(b\right)^2-4\left(a\right)\left(c\right)}}{2\left(a\right)}$$

• $$x=\frac{\left(b\right)\pm\sqrt{\left(b\right)^2-4\left(a\right)\left(c\right)}}{2a}$$

• $$x=-\left(b\right)\pm\sqrt{b\pm4\left(a\right)\left(c\right)}$$

Multiple Choice

Solve using the Quadratic Formula:

x² + 4x + 3 = 0

• x = 1 and x = 3

• x = 6 and x = -2

• x = -1 and x = -3

Multiple Choice

Solve 2x² + 7x - 15 = 0

• -3/2 or 5

• No Solution

• -5 or 3/2

• 0.7 or 5