Ax + By = C form of the given equation is –6x + y = –28.
Solution:
Given equation is y – 2 = 6(x – 5).
To write the equation in Ax + By = C format:
y – 2 = 6(x – 5)
y – 2 = 6x – 30
Add 2 on both sides of the equation.
y – 2 + 2 = 6x – 30 + 2
y = 6x – 28
Subtract 6x from both sides of the equation.
y – 6x = 6x – 28 – 6x
y – 6x = –28
Arrange the terms in the equation.
–6x + y = –28
This is in the form of Ax + By = C.
Here A = –6, B = 1 and C = –28.
Part 1: The general form for this matches y^2 = -4cx, which implies that this opens to the left. (Imagine assigning any value of y, whether positive or negative, which would result in a positive left-hand value. Then to match this sign, the value of x must be negative so that the right-hand side becomes positive as well.)
Part 2: The distance from the vertex to the directrix is given by c. This equation has its vertex at the origin (0, 0). If it opens to the left, the directrix is a vertical line to the right of the origin. This equation is y^2 = -4(1/2)x, so c = 1/2, and the directrix has the equation x = 1/2.
Part 3: The focus is inside the parabola, but it is the same distance from the vertex as the directrix. This distance is 1/2 units, and it will be to the left of the vertex. So the focus is at (-1/2, 0).
DE. AB, is going up BC, isn't decreasing or increasing. CD, isn't decreasing or increasing. Therefore your answer is DE.
