What is the equation of the parabola passing through (1,5), (0,6), and (2,3)?
What is the equation of the parabola passing through (1.5), (0.6), and (2,3)?
Is it a parable of 2 or 3 potency?
Also a circle cuts the three points.
(1,5), (0,6), and (2,3)
We have this form
y = a(x - h)^2 + k where "a" determines the width (and direction - "up" or "down" ) of the parabola, and (h,k) is the vertex
So we know that
5 = a ( 1 - h)^2 + k → 5 = a(1 -2h + h^2) + k → 5 = a -2ah + ah^2 + k (1)
6 = a(0 - h)^2 + k → 6 = ah^2 + k (2)
3 = a(2 - h)^2 + k → 3 = a(4 - 4h + h^2) + k → 3 = 4a -4ah +ah^2 + k (3)
Sub ( 2) into (1) and (3)
5 = a - 2ah + 6 → -1 = a - 2ah ( 4)
3 = 4a - 4ah + 6 → -3 = 4a - 4ah (5)
Multiply (4) by -2 and add it to (5)
-1 = 2a → a = -1/2
Using (4) to find h, we have
-1 = (-1/2) - 2 (-1/2)h
-1/2 = h
Using (2) to find k, we have
6 = (-1/2)(1/4) + k
k = 6 + 1/8 = 49/8
So..........our equation is
y = (-1/2)(x + 1/2)^2 + 49/8
Here's the graph with the points of interest : https://www.desmos.com/calculator/vnyrl52lp8
What is the equation of the parabola passing through (1,5), (0,6), and (2,3)?
Formula parabola:
y=ax2+bx+c
a, b, c = ?
P(0,6):6=02⋅a+0⋅b+c6=cP(1,5):5=12⋅a+1⋅b+c5=a+b+c|c=6(1)5=a+b+6P(2,3):3=22⋅a+2⋅b+c3=4a+2b+c|c=6(2)3=4a+2b+6
a, b = ?
(2)3=4a+2b+6|:21.5=2a+b+3(1)5=a+b+6(2)−(1):1.5−5=2a+b+3−(a+b+6)−3.5=2a+b+3−a−b−6−3.5=a−3−0.5=a5=a+b+6|a=−0.55=−0.5+b+65=5.5+b5−5.5=b−0.5=b
Formula parabola:
y=ax2+bx+c|a=−0.5b=−0.5c=6y=−0.5x2−0.5x+6