Answered

Find a number c such that the polynomial
p(x) = -x + 4x2 + cx3 - 8x4
has a zero at x =1/4

Answer :

Answer:

c = 2

Step-by-step explanation:

Since the polynomial has a zero at x = [tex]\frac{1}{4}[/tex] , then p([tex]\frac{1}{4}[/tex] ) = 0, then

p([tex]\frac{1}{4}[/tex] )

- [tex]\frac{1}{4}[/tex] + 4([tex]\frac{1}{4}[/tex] )² + c([tex]\frac{1}{4}[/tex] )³ - 8[tex](\frac{1}{4}) ^{4}[/tex] = 0

- [tex]\frac{1}{4}[/tex] + 4([tex]\frac{1}{16}[/tex] ) + c([tex]\frac{1}{64}[/tex] ) - 8([tex]\frac{1}{256}[/tex] ) = 0

- [tex]\frac{1}{4}[/tex] + [tex]\frac{1}{4}[/tex] + [tex]\frac{c}{64}[/tex] - [tex]\frac{1}{32}[/tex] = 0 , simplifying gives

[tex]\frac{c}{64}[/tex] - [tex]\frac{1}{32}[/tex] = 0 ( add [tex]\frac{1}{32}[/tex] to both sides )

[tex]\frac{c}{64}[/tex] = [tex]\frac{1}{32}[/tex] ( multiply both sides by 64 )

c = 2

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