Question

If two zeros of x³ + x² – 5x – 5 are √5 and –√5 , then its third zero is
A. 1
B. – 1
C. 2
D. – 2

Answer 1

answer : option (B) -1

two zeroes of x³ + x² - 5x - 5 are √5 and -√5

so, (x - √5) and (x + √5) are factors of x³ + x² - 5x - 5.

so, (x - √5)(x + √5) = x² - 5 is a factor of x³ + x² - 5x - 5 .

now, x² - 5)x³ + x² - 5x - 5 (x + 1

x³ - 5x

......................................

x² - 5

x² - 5

....................................

0

hence, another factor of given expression is x + 1.

so, third zero of given expression is x = -1

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Answer 2

Answer:

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