Which of the following represents the zeros of f(x) = 4x3 - 13x2 - 37x + 10?
5, -2, -1/4
5, -2, 1/4
5, 2, -1/4
5, 2, 1/4
Solution:
Using the Rational Zeros Theorem, which states that, if the polynomial f(x) = anxn + an - 1xn - 1 + ... + a1x + a0 has integer coefficients,
then every rational zero of f(x) has the form p/q where p is a factor of the constant term a₀ and q is a factor of the leading coefficient an.
Given:
Function f(x) = 4x3 - 13x2 - 37x + 10
Here,
p: ±1, ±2, ±5, ±10 which are all factors of constant term 10.
q: ±1, ±2, ±4 which are all factors of the leading coefficient 4
All possible values are
p/q: ±1, ±2, ±5, ±10, ±1/2, ±1/4, ±5/2, ±5/4
From the given options we can select only ±5/4, ±2/4, ±1/4 to verify the roots.
f(x) = 4x3 - 13x2 - 37x + 10
f(5/4) = 4(5/4)3 - 13(5/4)2 - 37(5/4) + 10 = -48.75
f(5/4) = 4(-5/4)3 - 13(-5/4)2 - 37(-5/4) + 10 = 28.125
f(2/4) = 4(2/4)3 - 13(2/4)2 - 37(2/4) + 10 = -11.25
f(-2/4) = 4(-2/4)3 - 13(-2/4)2 - 37(-2/4) + 10 = 24.75
f(1/4) = 4(1/4)3 - 13(1/4)2 - 37(1/4) + 10 = 0
The given options are not the zeros of the given polynomial.
However on verification it is identified that 5, -2 and 1/4.
Which of the following represents the zeros of f(x) = 4x3 - 13x2 - 37x + 10?
Summary:
The zeros of the f(x) = 4x3 - 13x2 - 37x + 10 are 5, -2, 1/4. We have used rational root theorem to find the zeros.
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