To find the focus of the parabola, we need to convert the given general equation into the standard form (y−k)2=4a(x−h).
1. Rearrange the Equation:
Group the y terms on one side and move the x and constant terms to the right:
Divide the entire equation by 4 to simplify the y2 coefficient:
2. Complete the Square for y:
To complete the square for y2−5y, add (25)2=425 to both sides:
3. Factor out the Coefficient of x:
4. Identify Standard Parameters:
Comparing this with (y−k)2=−4a(x−h):
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Vertex (h,k): (−27,25)
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4a Value: 4a=3⟹a=43
5. Calculate the Focus:
For a parabola opening to the left, the focus is given by (h−a,k):
To solve the x-coordinate, find a common denominator:
So, the focus is (−417,25).
Conclusion:
The coordinates of the focus are (−417,25).
Correct Option:
C) (−417,25)