Th11.19 Solving using the Quadratic Formula

Identify the a, b, c for the following quadratic equation:

2x² -x +5=0

• a= 2 b=0 c=5

• a= 2 b=-1 c=5

• a= 2 b=1 c=5

• a= 2 b=0 c=-5

Identify the a, b, c for the following quadratic equation:

x² = 3x + 3

• a= 1 b=3 c=3

• a= 1 b=3 c=-3

• a= 1 b=-3 c=-3

• a= 1 b=-3 c=3

Identify the a, b, c for the following quadratic equation:

-x² + 5 = - 5x

• a= -1 b= 5 c=5

• a= 1 b= -5 c=5

• a= -1 b= -5 c=5

• a= 1 b= 5 c= -5

Find the discriminant: D = b² - 4ac

x^2_5x -24 =0

• -71

• -121

• 71

• 121

Use the discriminant found above to determine the number of solutions:

x^2_5x -24 =0

• one real solution

• two real solutions

• no solutions (imaginary)

Find the discriminant: D = b² - 4ac

2x² =-5x +1 (Hint: standard form?)

• 17

• 33

• -17

• -33

Use the discriminant found above to determine the number of solutions:

2x² =-5x +1

• one real solution

• two real solutions

• no solutions (imaginary)

Find the discriminant and use it to determine the number of solutions:

9x² =6x - 1

• one real solution

• two real solutions

• no solutions (imaginary)

What is the Quadratic Formula?

• $x=\frac{-b\pm\sqrt{b^2-2ac}}{4a}$

• $x=\frac{-b\pm\sqrt{b^2+4ac}}{2a}$

• $x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}$

• $x=\frac{-b\pm\sqrt{b-4ac}}{2a}$

Which answer below shows the correct quadratic formula for:

 $x^2+10x+21=0$  

•  $x=\frac{-10\pm\sqrt{\left(10\right)^2-4\left(1\right)\left(21\right)}}{2\left(1\right)}$  

•  $x=\frac{10\pm\sqrt{\left(10\right)^2-4\left(1\right)\left(21\right)}}{2\left(1\right)}$  

•  $x=\frac{-10\pm\sqrt{\left(10\right)^2-2\left(1\right)\left(21\right)}}{4\left(1\right)}$  

•  $x=\frac{-10\pm\sqrt{\left(10\right)-4\left(1\right)\left(21\right)}}{2\left(1\right)}$