Using factor theorem, factorize of the polynomials:
$x^{4}-7 x^{3}+9 x^{2}+7 x-10$
Given, $f(x)=x^{4}-7 x^{3}+9 x^{2}+7 x-10$
The constant term in f(x) is 10
The factors of 10 are ± 1, ± 2, ± 5, ±10
Let, x – 1 = 0
=> x = 1
Substitute the value of x in f(x)
$f(x)=14-7(1)^{3}+9(1)^{2}+7(1)-10$
= 1 – 7 + 9 + 7 – 10
= 10 – 10
= 0
(x – 1) is the factor of f(x)
Similarly, the other factors are (x + 1), (x – 2), (x – 5)
Since, f(x) is a polynomial of degree 4. So, it cannot have more than four linear factor.
So, f(x) = k(x – 1)(x + 1)(x – 2)(x – 5)
$\Rightarrow x^{4}-7 x^{3}+9 x^{2}+7 x-10=k(x-1)(x+1)(x-2)(x-5)$
Put x = 0 on both sides
0 – 0 + 0 – 10 = k(-1)(1)(-2)(-5)
– 10 = k(-10)
=> k = 1
Substitute k = 1 in f(x) = k(x – 1)(x + 1)(x – 2)(x – 5)
f(x) = (1)(x – 1)(x + 1)(x – 2)(x – 5)
= (x – 1)(x + 1)(x – 2)(x – 5)
So, $x^{4}-7 x^{3}+9 x^{2}+7 x-10$
= (x – 1)(x + 1)(x – 2)(x – 5)