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Knowing that –3 is the root of P (x) = x³ + 4x² – ax + 1, calculate the value of a and mark the correct answer.
Question
Knowing that –3 is the root of P (x) = x³ + 4x² – ax + 1, calculate the value of a and mark the correct answer.
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Mathematics
3 years
2021-08-13T12:52:58+00:00
2021-08-13T12:52:58+00:00 1 Answers
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Answers ( )
Answer:
value of a is -3.33
or in fraction -10/3
Step-by-step explanation:
If -3 is the root of P(x)
then
P(-3) = 0
then we substitute -3 in place of x in the given equation
P (x) = x³ + 4x² – ax + 1
P (-3) = -3³ + 4*-3² – a(-3) + 1
=> 0 = -27 + 36 + 3a + 1
=> 0 = 10 + 3a
=> 3a = -10
=> a = -10/3 = -3.33
Thus, value of a is -3.33