Answer the following.

Expand $\left(x+5\right)\left(x-5\right)$(x+5)(x−5).

Hence factorise $x^2-25$x2−25.

Which positive integer must go in the spaces to make the statement true?

What expression must go in the space to make the statement true?

One linear factor of $x^2-49$x2−49 is $x+7$x+7. What is the other factor?