How do you solve $3x^2 - 15x + 18 = 0$ using the quadratic formula?

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Answer 1 · 2016-07-10T15:45:41

The answers are $x = 2, 3$ .

$x = (-b +- sqrt(b^2 - 4ac))/2a$

And in your polynomial:
$a = 3$
$b = -15$
$c = 18$

So plugging those in we get:

$x = (15 +- sqrt(15^2 - 4*3*18))/(2*3)$
$= (15 +- sqrt(225 - 216))/6$
$= (15 +- sqrt(9))/6$
$= (15 +- 3)/6$

So our two answers are:

$x = (15 - 3)/6 = 12/6 = 2$
and
$x = (15 + 3)/6 = 18/6 = 3$

How do you solve 3x^2 - 15x + 18 = 0 3x^2 - 15x + 18 = 0 using the quadratic formula?