Question

Which function has real zeros at x = 3 and x = 7?

f(x) = x2 + 4x – 21
f(x) = x2 – 4x – 21
f(x) = x2 – 10x + 21
f(x) = x2 – 10x – 21

Answer 1

If it has real zeros at x=3 and 7, the factors of f(x) are:

(x-3)(x-7) so f(x) is

f(x)=x^2-10x+21

Answer 2

Option 3 -
`f(x)=x^2-10x+21`

Explanation:

To find : Which function has real zeros at x = 3 and x = 7?

Solution :

We have given the roots of the function i.e at x=3 and x=7

So, The factor form is (x-3) and (x-7).

Multiply both the roots to find the function,

`f(x)=(x-3)(x-7)`

`f(x)=x^2-7x-3x+21`

`f(x)=x^2-10x+21`

Therefore, The required function is
`f(x)=x^2-10x+21`

So, option 3 is correct.