Jill Say that 23/1000 can be written as 0.23 which explain whether or not Jill is correct

No, Jill is incorrect because 23/1000 and 0.23 are not equivalent.  But 23/100 is equivalent to 0.23 and 0.023 is equivalent 23/1000

x = -1

Step-by-step explanation:

Add -6x to both sides to get: 3x^2 + 6x + 3 = 0

Factor out 3: 3(x^2 + 2x + 1) = 0

Factor inside the parentheses: 3(x + 1)(x + 1) = 0

Zero Product Property: x + 1 = 0

Solve: x = -1