1) Expressing your answer in interval notation, find all values of k such that the parabola y=x^2 + kx + 11 does not intersect the line y=2.
2) Expressing your answer in interval notation, find all values of s such that x(x-2)^2(x+1)<0.
3)Determine the range of the function g(x)=5x^2-2x+1. Enter your answer in interval notation.
1) Expressing your answer in interval notation, find all values of k such that the parabola y=x^2 + kx + 11 does not intersect the line y=2.
Let's see where the parabola DOES intersect y = 2
x^2 + kx + 11 = 2
x^2 + kx + 9 = 0
Where the discriminant is ≥ 0, we will have real solutions....so....
k^2 - 4*9 ≥ 0
k^2 ≥ 36
So.....the intervals where the parabola will intersect the line y = 2 are when k =
(-infinity, -6 ] U [6, infinity )
So.....when -6 < k < 6 the parabola WILL NOT intersect the line y = 2
2) Expressing your answer in interval notation, find all values of s such that x(x-2)^2(x+1)<0.
I think you must mean "x", not "s."
x ( x - 2)^2 (x + 1) < 0
Note that when x ≥ 0.... the result will be ≥ 0
When -1 < x < 0....the result will be < 0
When -inf < x < -1.....the result will be ≥ 0
So.....this will be < 0 on the interval ( -1, 0 )
3)Determine the range of the function g(x)= 5x^2-2x+1. Enter your answer in interval notation.
This is a parabola that turns upward
The x coordinate of the vertex is 2/ [ 2 * 5] = 1/5
The y coordinate of the vertex is
5(1/5)^2 - 2(1/5) + 1 =
1/5 - 2/5 + 1 =
4/5
So...the range is [ 4/5, infinity )