Question

Which shows the correct substitution of the values a, b, and c from the equation 0 = 4x2 + 2x – 1 into the quadratic formula below?

Quadratic formula: x =

Answer 1

For this case we have a quadratic equation given by:

$4x ^ 2 + 2x-1 = 0$

The roots are found by means of the quadratic formula below:

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

Where:

$a = 4\\b = 2\\c = -1$

So, we have:

$x = \frac {-2 \pm \sqrt {2 ^ 2-4 (4) (- 1)}} {2 (4)}$

Or in an equivalent way we have:

$x = \frac {-2 \pm \sqrt {2 ^ 2 + 4 (4) (1)}} {2 (4)}$

Answer:

The correct option will be:

$x = \frac {-2 \pm \sqrt {2 ^ 2-4 (4) (- 1)}} {2 (4)}$

Answer 2

Answer:

a = 4, b = 2 and c= -1

Step-by-step explanation:

Quadratic formula: x =√[-b ± v(b² - 4ac)]/2a

Here quadratic equation is  4x2 + 2x – 1

a = 4, b = 2 and c= -1

x =[-b ± √(b² - 4ac)]/2a

 = [-2 ± √(2² - 4*4*-1)]/2*4

 = [-2 ± √(4  + 16)]/8

 = [-2 ± √20)]/8

 = [-2 ± 2√5)]/8

 =  [-1 ± √5)]/4

x = [-1 ± √5)]/4