SOLUTION: Hi, Can yo please help me find the domain and range of {{{-2x^2-4x+6}}} and where it would be increasing and decreasing. I tried solving this over and over but i got the dom

Algebra ->  Functions -> SOLUTION: Hi, Can yo please help me find the domain and range of {{{-2x^2-4x+6}}} and where it would be increasing and decreasing. I tried solving this over and over but i got the dom      Log On


   

Question 974203: Hi,
Can yo please help me find the domain and range of -2x%5E2-4x%2B6 and where it would be increasing and decreasing.
I tried solving this over and over but i got the domain of all real numbers and the range of (-infinity,-6] but i don't know if that's right.
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
Complete the square to put into standard form. You can read everything you need from it.

-2%28x%5E2%2B2x-3%29
-2%28x%5E2%2B2x%2B1-1-3%29
-2%28%28x%2B1%29%5E2-4%29
-2%28x%2B1%29%5E2%2B8

The vertex is a maximum value for the expression, at (-1,8).
The range is ( -infinity, 8].
Increasing from the left until negative 1; decreasing from negative 1 to the right.
Saying in interval notation better: Increasing on ( -infin, -1 ); decreasing on ( -1, infinity ).