Answer:
The coefficients for the quadratic regression curve are
a = (-2/3) = -0.6667
b = (11/3) = 3.6667
c = 1 = 1.0000
y(x) = -0.6667x² + 3.6667x + 1.0000
Step-by-step explanation:
Quadratic regression curve gives a general expression of
y = ax² + bx + c
And the points on the curve include
(1, 4), (3, 6), (4, 5), (5, 2)
Taking the points one at a time and substituting them into general quadratic curve expression
(1, 4), x = 1, y = 4
y = ax² + bx + c
4 = a + b + c (eqn 1)
(3, 6), x = 3, y = 6
6 = a(3²) + b(3) + c
6 = 9a + 3b + c (eqn 2)
(4, 5), x = 4, y = 5
5 = a(4²) + b(4) + c
5 = 16a + 4b + c (eqn 3)
Combining the 3 equations and solving simultaneously
4 = a + b + c
6 = 9a + 3b + c
5 = 16a + 4b + c
From eqn 1, c = 4 - a - b
Substituting this into eqn 2 and 3, we have
6 = 9a + 3b + 4 - a - b
2 = 8a + 2b (*)
5 = 16a + 4b + 4 - a - b
1 = 15a + 3b (**)
8a + 2b = 2
15a + 3b = 1
a = (-2/3), b = (11/3)
c = 4 - a - b
c = 4 - (-2/3) - (11/3)
c = 1
Hence, the coefficients for the quadratic regression curve are
a = (-2/3) = -0.6667
b = (11/3) = 3.6667
c = 1 = 1.0000
y(x) = -0.6667x² + 3.6667x + 1.0000
Hope this Helps!!!
