Which of the following is a factor of xy + 3y - 7x - 21?
5, x + 3, x² - 3x + 9, All of the above

Solution:

'Factor' is a term used to express a number as a product of any two numbers. 

Factorization is a method of finding factors for any mathematical object, be it a number, a polynomial or any algebraic expression.

The given expression is

xy + 3y - 7x - 21 

Let us take out the common factors

= (xy + 3y) - (7x + 21)

Here

= y (x + 3) - 7 (x + 3)

So we get

= (y - 7) (x + 3)

Therefore, the factors are (x + 3) and (y - 7).

Which of the following is a factor of xy + 3y - 7x - 21?
5, x + 3, x² - 3x + 9, All of the above

Summary:

The factors of xy + 3y - 7x - 21 are (x + 3) and (y - 7).