Question

URGENT PLEASE Solve the equation using the quadratic formula. 3x^2 - 18 = -6

Answer 1

Answer:

x = 2 and x = -2

Step-by-step explanation:

The quadratic formula of a quadratic of the form ax² + bx + c is:

x = $\frac{-b+\sqrt{b^2-4ac} }{2a}$ or x = $\frac{-b-\sqrt{b^2-4ac} }{2a}$

Here, our equation is: 3x² - 18 = -6. Let's move all the terms to one side:

3x² - 12 = 0

a = 3 and c = -12. Notice that since there's no x term, b = 0.

Plug these into the quadratic formula:

x = $\frac{0+\sqrt{0^2-4*3*(-12)} }{2*3}=\frac{\sqrt{144} }{6}=12/6=2$  

or

x = $\frac{0-\sqrt{0^2-4*3*(-12)} }{2*3}=\frac{-\sqrt{144} }{6}=-12/6=-2$

So, x = 2 and x = -2.

Answer 2

Answer: x = -2, x = 2

Step-by-step explanation:

The quadratic formula:

$x=\frac{-b+\sqrt{b^2-4ac} }{2a} \\\\AND\\\\x = \frac{-b-\sqrt{b^2-4ac} }{2a}$

You can find the variables a, b, and c in the standard form of a quadratic equation:

$f(x)=ax^2 + bx+c$

Your equation:

$f(x)=3x^2 + 0x -12$

The variables are:

a = 3

b = 0

c = -12

Substitute those for the variables in the quadratic formula:

$x=\frac{-0+\sqrt{0-(4*3*-12)}}{2(3)} \\\\AND\\\\x=\frac{-0-\sqrt{0-(4*3*-12)}}{2(3)}$

You can simplify this to get:

$x=\frac{-\sqrt{144}}{6}$

(or positive square root of 144.)

The square root of 144 is 12, and 12/6 = 2.

The x-values are -2 and 2.