Arun1992 wrote:
Point P lies on
y=x2−1 and Point Q lies on
y=−x2+1
Quantity A |
Quantity B |
minimum y coordinate value of Point P |
maximum y coordinate value of Point Q |
Although it helps, we don't need to know the actual shapes of the two parabolas.
Key property: k2≥0 for all values of k
In other words, k2 is greater than or equal to 0 for all values of kQuantity A: minimum y coordinate value of Point P
Since P is a point on the parabola, its coordinates must satisfy the parabola's equation
y=x2−1So, to find the minimum value of
y, we are really finding the minimum value of
x2−1 Since
x2≥0 for all values of
x, the minimum of
x2≥0 is
0, which means the minimum value of
x2−1 is
0 - 1 =
-1 Quantity B: maximum y coordinate value of Point Q
Applying the same logic, we know that the coordinates of point Q must satisfy the equation
y=−x2+1, which we can also write as
y=−(x2)+1Key property: −(k2)≤0 for all values of kSo, to find the maximum value of
y, we are really finding the maximum value of
−(x2)+1 Since the maximum value of
−(x2) is
0, we know the maximum value of
−(x2)+1 is
0 + 1 =
1 So, we have:
Quantity A:
-1 Quantity B:
1 Answer: B