Question

Rhett is solving the quadratic equation 0= x2 – 2x – 3 using the quadratic formula. Which shows the correct substitution of the values a, b, and c into the quadratic formula?

Answer 1

Hi, the quadratic formula is: $\boxed{X= \dfrac{-b \pm \sqrt{b ^{2}-4ac} }{2a}}$

Values:
a = 1; b = - 2; c = - 3
SOLVING:

$0=X ^{2}-2X-3$

$X ^{2}-2X-3=0$

$X= \dfrac{-(-2) \pm \sqrt{(-2) ^{2}-4(1)(-3) } }{2(1)}$

$X= \dfrac{2 \pm \sqrt{4+12} }{2}$

$X= \dfrac{2 \pm \sqrt{16} }{2}$

$X= \dfrac{2 \pm4}{2}$

Getting X₁:

X₁ = $\dfrac{2+4}{2}$

X₁ = $\dfrac{6}{2}$

X₁ = $\boxed{ \boxed{ \textbf{3}}}\ ===>\ The\ first\ solution.$


Getting X₂:

X₂ = $\dfrac{2-4}{2}$

X₂ = $\dfrac{-2}{2}$

X₂ = $\boxed{ \boxed{ \textbf{-1}}}\ ===>\ The\ second\ solution.$

GOOD LUCK...!!!