One factor of f(x) = 4x3 - 4x2 - 16x + 16 is (x - 2). What are all the roots of the function? Use the Remainder Theorem.
Solution:
f(x) = 4x3 - 4x2 - 16x + 16 [Given]
One factor is (x - 2)
By applying the remainder theorem,
f(x) = (x-2)·q(x) + r(x), where q(x) = quotient polynomial and r(x) = remainder polynomial.
r(x) = 0 as (x-2) is a factor of f(x)
f(x) = (x-2)·q(x)
q(x) = f(x)/ (x-2)
[4x3 - 4x2 - 16x + 16]/ (x - 2)
= [4x2 (x - 1) - 16 (x - 1)]/ (x - 2)
By further simplification
= [(x - 1) (4x2 - 16)]/ (x - 2)
Taking out 4 as common
= [(x - 1) 4 (x2 - 4)]/ (x - 2)
Using the algebraic identity a2 - b2 = (a + b) (a - b)
= [(x - 1) 4 (x + 2) (x - 2)]/ (x - 2)
= [4 (x - 1) (x - 2) (x + 2)]/ (x - 2)
Therefore, the roots are 2, -2 and 1.
One factor of f(x) = 4x3 - 4x2 - 16x + 16 is (x - 2). What are all the roots of the function? Use the Remainder Theorem.
Summary:
One factor of f(x) = 4x3 - 4x2 - 16x + 16 is (x - 2). All the roots of the function are 2, -2 and 1.
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