Answer: 
Step-by-step explanation:
We know that the standard quadratic equation is ax^2+bx+c=0
Let's compare all the given equation to it and , find discriminant.
1. a=2, b= -7, c=-9
So it has 2 real number solutions.
2. a=1, b=-4, c=4

So it has only 1 real number solution.
3. a=4, b=-3, c=-1

So it has 2 real number solutions.
4. a=1, b=-2, c=-8
So it has 2 real number solutions.
5. a=3, b=5, c=3

Thus it does not has real solutions.
Answer:
C
Step-by-step explanation:
Because equation C is telling us that the amount of caffeine is less than 400.
Hope this will help
Four and Eleven Hundredth
Let us use the Pythagorean theorem in identifying what triangle can be formed.
Let us assume that the 2 wooden dowels each measure 8 inches. We cut off one wooden dowel into half, so it becomes 2 pcs of 4 inches each.
The 3 wooden dowels now measure, 4 inches, 4 inches, and 8 inches.
The Pythagorean theorem states:
a² + b² = c²
4² + 4² = 8²
16 + 16 = 64
34 ≠ 64
The measure of the cut wooden dowel must be longer than the uncut wooden dowel to create a triangle.
I also tried this on a piece of paper, I cut each piece according to the assumed measure. No triangle can be formed under this activity.