3. Find the factors

Use the identity to solve the following:

 

Identity: $(x + a)(x + b) = x^2 + x(a + b) + ab$

 

Expression: $r^2 + 21r + 38$

 

The factors are $($$)$ and $($$)$.

 

[Note: In case of multiple expressions, enter in the order given in the question. In case of multiple operations, always enter the '$+$' operation first. When two factors deal with constants, enter the factor with the largest constant first followed by the number with the smallest constant.]