Question

Solve: 16x^2 − 80 = 0 using the quadratic formula

Answer 1

For this case we have the following quadratic equation:

$16x ^ 2-80 = 0$

Applying the quadratic formula we have:

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

Where:

$a = 16\\b = 0\\c = -80$

Substituting we have:

$x = \frac {-0 \pm \sqrt {0 ^ 2-4 (16) (- 80)}} {2 (16)}\\x = \frac {\pm \sqrt {4 (16) (80)}} {32}\\x = \frac {\pm \sqrt {5120}} {32}\\x = \frac {\pm71.55} {32}$

We have two roots:$x_ {1} = \frac {-71.55} {32} = - 2.24\\x_ {2} = \frac {71.55} {32} = 2.24$

Answer:

Option B

Answer 2

Answer:

B

Step-by-step explanation:

Using the quadratic formula with

a = 16, b = 0 and c = - 80, then

x = ( 0 ± $\sqrt{0-(4(16)(-80)}$ / 32

  = ± $\frac{\sqrt{5120} }{32}$

x = - $\frac{\sqrt{5120} }{32}$ , x = $\frac{\sqrt{5120} }{32}$

x = - 2.24, x = 2.24 ( to the nearest hundredth )