How do you solve 3x squared plus 9x plus 2 by completing the square?

Answer 1

3x2 + 9x + 2 is an expression; it is NOT an equation. You cannot solve an expression.

However, if you did have an equation: 3x2 + 9x + 2 = 0

Then dividing through by 3 gives: x2 + 3x + 2/3 = 0

or x2 + 3x = - 2/3

Completing the square on the left (add 9/4 to both sides) : x2 + 3x + 9/4 = 9/4 - 2/3 = 19/12

(x + 3/2)2 = 19/12

(x + 3/2) = +/- sqrt(19/12)

So x = -3/2 +/- sqrt(19/12)