Question

14. If 1 and -2 are two zeros of the polynomial (r - 4r -7x + 10), find its third zero. TE​

Answer 1

Answer:

Let f(x)=x

3−4x 2−7x+10

Given : 1 and −2 are the zeros of the given polynomial therefore (x−1) and (x+2) are factors of f(x)

Consequently ,(x−1)(x+2)=(x2+x−2) is a factor of f(x)

Divide x3−4x2−7x+10 by (x2+x−2)

put f(x)=0

(x2+x−2)(x−5)=0

(x−1)(x+2)(x−5)=0

x=1 or x=−2 or x=5

hence , the third zero is 5.