### Substitution into Formulae − 2

Substitution can also be applied to letters that have indices

#### Example 1. What is the value of 2 + 3c

^{2}when c = 4?#### Example 2. What is the value of a + 7b

^{2}when a = 2 and b = 5?#### Example 3. What is the value of x + yz

^{2}when x = −5, y = 4 and z = −6?

2 + 3c^{2} | = 2 + 3(4^{2}) |

= 2 + (3 × 16) | |

= 2 + 48 | |

= 50 |

a + 7b^{2} | = (2) + 7(5^{2}) |

= 2 + (7 × 25) | |

= 2 + 175 | |

= 177 |

x + yz^{2} | = (−5) + (4) (−6)^{2} |

= −5 + (4 × 36) | |

= −5 + 144 = 139 | |

= 139 |

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