Combination Theorem for Sequences/Real

Theorem

Let $\sequence {x_n}$ and $\sequence {y_n}$ be sequences in $\R$.

Let $\sequence {x_n}$ and $\sequence {y_n}$ be convergent to the following limits:

$\ds \lim_{n \mathop \to \infty} x_n = l$

$\ds \lim_{n \mathop \to \infty} y_n = m$

Let $\lambda, \mu \in \R$.

Then the following results hold:

Sum Rule

$\ds \lim_{n \mathop \to \infty} \paren {x_n + y_n} = l + m$

Difference Rule

$\ds \lim_{n \mathop \to \infty} \paren {x_n - y_n} = l - m$

Multiple Rule

$\ds \lim_{n \mathop \to \infty} \paren {\lambda x_n} = \lambda l$

Combined Sum Rule

$\ds \lim_{n \mathop \to \infty} \paren {\lambda x_n + \mu y_n} = \lambda l + \mu m$

Product Rule

$\ds \lim_{n \mathop \to \infty} \paren {x_n y_n} = l m$

Quotient Rule

$\ds \lim_{n \mathop \to \infty} \frac {x_n} {y_n} = \frac l m$

provided that $m \ne 0$.