Question

If -1 is a zero of the polynomial p(x)=ax^3-x^2+x+21 find the value of 'a'if

Answer 1

Answer:

19

a = 19

Step-by-step explanation:

Given,

p(x) = ax^3-x^2+x+21

On zero of polynomial = -1

Then, by using factor theorem and replacing the value of x by -1 in p(x), we get,

p(-1) = a(-1)^3 - (-1)^2 + (-1) + 21

Then,

=> a(-1)^3 - (-1)^2 + (-1) + 21 = 0

=> a(-1) - (1) - 1 + 21 = 0

=> -a - 1 - 1 + 21 = 0

=> a = 21 - 2

=> a = 19

Hence, a = 19

Answer 2

Answer:

a=21

Step-by-step explanation:

ax^3-x^2+x+21 =0

= a(-1)^3+(-1)^2+(-1)+21 =0

= -a+1-1+21 =0

= -a+21 =0

= -a = 0-21

= a = 21

........ hope it helps..........

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