__Matrix Basics__A matrix is a grid of entries in row/column format. Matrix entries are denoted by a

_{i}_{j} where is the row and j is the column

a_{11} | a_{12} | a_{13} |

a_{21} | a_{22} | a_{23} |

a_{31} | a_{32} | a_{33} |

Matrix addition and subtraction involves adding or subtracting respective matrix entries

a_{11} | a_{12} | a_{13} |

a_{21} | a_{22} | a_{23} |

a_{31} | a_{32} | a_{33} |

b_{11} | b_{12} | b_{13} |

b_{21} | b_{22} | b_{23} |

b_{31} | b_{32} | b_{33} |

a_{11} + b_{11} | a_{12} + b_{12} | a_{13} + b_{13} |

a_{21} + b_{21} | a_{22} + b_{22} | a_{23} + b_{23} |

a_{31} + b_{31} | a_{32} + b_{32} | a_{33} + b_{33} |