Answer:
In a quadratic equation of the shape:
y = a*x^2 + b*x + c
we hate that the discriminant is equal to:
D = b^2 - 4*a*c
This thing appears in the Bhaskara's formula for the roots of the quadratic equation:

You can see that the determinant is inside a square root, this means that if D is smaller than zero we will have imaginary roots (the graph never touches the x-axis)
If D = 0, the square root term dissapear, and this implies that both roots of the equation are the same, this means that the graph touches the x axis in only one point, wich coincides with the minimum/maximum of the graph)
If D > 0 we have two different roots, so the graph touches the x-axis in two different points.
Plug in the value of -2 and -8
(-2)^2 - (-8) + 1
4 + 8 + 1 = 13
-1/4 is between -2/6 and -1/6
Answer:
30%
Step-by-step explanation:
7+14+9=30
10% of 30 is 3.
3 goes into nine 3 times so you times 10% by 3 to get 30%.
Answer:
x = 10
Step-by-step explanation:
3x - 9 = 21
add 9 on both sides:
⇒ 3x - 9 + 9 = 21 + 9
⇒ 3x = 30
divide 3 on both sides:
⇒ 
⇒ x = 10
to check answer, substitute x by 10 on the original equation:
⇒ 3x - 9 = 21
⇒ 3 x 10 - 9 = 21
⇒30 - 9 = 21
⇒ 21 = 21