What is the range of the graph of y=-2x^2-8x-7 ?

TTs160712_jen34016_1
Function
2( ) 2 8 7f x x x   

Now
F(0) = -7
F(-infinity)= - infinity
F(infinity)= + infinity
Since the coefficient of square term is -2 and hence it will be a downwards parabola and will reach –
infinity
Now we have to find the maximum value of function...