Question

Consider,p(x)=(x+2)(x+k)(x-7) if p(5)=0,the value of k is

Answer 1

Answer:

k = –5

Note:

★ If the expression for any polynomial p(x) is given , then to fine p(a) we just need to put x = a everywhere in the expression of p(x) .

Solution:

• Given : p(x) = (x+2)(x+k)(x-7) , p(5) = 0

• To find : k = ?

We have ;

p(x) = (x+2)(x+k)(x-7)

Also,

It is given that , p(5) = 0 .

Thus,

=> p(5) = 0

=> (5 + 2)(5 + k)(5 - 7) = 0

=> 7•(k + 5)•(-2) = 0

=> -14•(k + 5) = 0

=> k + 5 = 0

=> k = -5

Hence , k = –5