Question

Solve each equation 3x^2=80

Answer 1

Answer:

$x = \frac{4\sqrt{15}}{3}, x = \frac{-4\sqrt{15}}{3}$

or

$x = \frac{\pm4\sqrt{15}}{3}$

Step-by-step explanation:

Hello!

Use the quadratic formula: $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$

First, let's convert our equation to standard form of a Quadratic: ax² + bx + c = 0

3x² = 80

3x² - 80 = 0

Note, thats the value of b will be 0, as there is no "bx"

Now, solve:

• $x = \frac{-(0) \pm \sqrt{(0)^2 - 4(3)(-80)}}{2(3)}$        Plug in values
• $x = \frac{\pm\sqrt{960}}{6}$                              Simplify the radical (Discriminant)
• $x = \frac{\pm8\sqrt{15}}{6}$                              Pull out perfect squares
• $x = \frac{4\sqrt{15}}{3}, x = \frac{-4\sqrt{15}}{3}$              Reduce factors

 

The solutions are $x = \frac{4\sqrt{15}}{3}, x = \frac{-4\sqrt{15}}{3}$