A parabola passes through the points (7,1), (12,15), (14,9), and (20,t). What is the value of t?
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Find the equation of the parabola.
y = ax^2 + bx + c
Solve for a, b & c using the 3 points given.
49a + 7b + c = 1
144a+12b + c = 15
196a+14b + c = 9
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Solve for a, b & c
I would use a matrix:
|y x^2 x 1|
|y1 x1^2 x1 1|
|y2 x2^2 x2 1| = 0
|y3 x3^2 x3 1|
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Sub 20 for x in the equation to find t.