Which one of the following is the second degree polynomial function f(x) where f(0) = 5, f(-1) = 10 and f(1) = 6?
Which one of the following is the second degree polynomial function f(x) where f(0) = 5, f(-1) = 10 and f(1) = 6? Correct Answer 3x<sup>2</sup> - 2x + 5
Concept:
General form of a second degree polynomial function is: P (x) = a0 + a1 × x + a2 × x2, where a0, a1 and a2 are real coefficients and a2 ≠ 0.
Calculation
As we know that, general form of a second degree polynomial function is: P (x) = a0 + a1 × x + a2 × x2, where a0, a1 and a2 are real coefficients and a2 ≠ 0.
Let f(x) = a × x2 + b × x + c where a, b and c are real coefficients and a ≠ 0.
Given: f(0) = 5, f(-1) = 10 and f(1) = 6.
⇒ f(0) = c = 5
⇒ f(- 1) = a - b + 5 = 10 ----(1)
⇒ f(1) = a + b + 5 = 6 ---(2)
By adding (1) and (2), we get
⇒ 2a + 10 = 16 ⇒ a = 3.
Now by substituting a = 3 in equation (1) we get,
⇒ 3 - b + 5 = 10 ⇒ b = - 2.
Hence, f(x) = a × x2 + b × x + c = 3x2 - 2x + 5.