PROBLEM
.pembuat fungsi nol polinomial f(x)=4x4+8x3−3x2−7x−2 adalah ...
A. x=−2 atau x=−1 atau x=−1/2
B. x=−2 atau x=1 atau x=−1/2
C. x=2 atau x=−1 atau x=−1/2
D. x=2 atau x=1 atau x=−1/2
E. x=−2 atau x=1 atau x=1/2
STEP 1
1. We are given the polynomial function f(x)=4x4+8x3−3x2−7x−2.
2. We need to find the roots of the polynomial, i.e., the values of x for which f(x)=0.
3. We have multiple choice options to evaluate.
STEP 2
1. Use the Rational Root Theorem to identify possible rational roots.
2. Test the possible roots using synthetic division or direct substitution.
3. Determine which option contains the correct roots.
STEP 3
Apply the Rational Root Theorem. The possible rational roots are the factors of the constant term −2 divided by the factors of the leading coefficient 4.
Possible rational roots: ±1,±2,±21,±41.
STEP 4
Test each possible root by substituting into f(x) to see if it equals zero.
Test x=−2:
f(−2)=4(−2)4+8(−2)3−3(−2)2−7(−2)−2 f(−2)=4(16)+8(−8)−3(4)+14−2 f(−2)=64−64−12+14−2 f(−2)=0 x=−2 is a root.
STEP 5
Test x=1:
f(1)=4(1)4+8(1)3−3(1)2−7(1)−2 f(1)=4+8−3−7−2 f(1)=0 x=1 is a root.
STEP 6
Test x=−21:
f(−21)=4(−21)4+8(−21)3−3(−21)2−7(−21)−2 f(−21)=4(161)+8(−81)−3(41)+27−2 f(−21)=41−1−43+27−2 f(−21)=0 x=−21 is a root.
SOLUTION
Based on the tests, the roots are x=−2, x=1, and x=−21.
The correct option is:
B. x=−2 or x=1 or x=−21
The correct answer is option B.
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