CBSE Class 11-science Answered
Find the equation of the parabola whose focus is (0,-7) and vertex is (0,0)
The axis is the y - axis, hence the parabola is either an upward or a downward parabola with equations x2 = 4ay or x2 = -4ay respectively. Since focus is a = -7 we use the equation x2 = -4ay.
Hence the equation is x2 = -4 7 y
x2 = -28y.
Alert! The negative sign signifies the type of parabola. Do not replace a as -7 for the sign is considered in the equation itself.