# 8 multiple choice ECET 345

**1. **(TCO 1) A signal that is a function of time has following properties or the following applies to it.(Points : 4) it is impossible to change the properties of a signal.

A signal can be modified by a system which applies a transformation to it.

an electrical signal can only be transformed into an electrical signal.

an electrical signal can only be transformed into a non-electrical signal.

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5.5 sin(ωt). 6 sin(ωt – π/4). 6 sin(ωt + π/4). 5.5 sin(ωt – π/4). |

y = x y= 2 x + 2 y = 2x |

y(n) = , value at n = 2 is -1 y(n) = , value at n = 2 is 0.0174 y(n) = , value at n = 2 is 0 y(n) = , value at n = 2 is 0.841 |

No, it is not violated. Yes, it is violated. Insufficient data to answer the question Question cannot be answered because sampling time is unknown |

15. pi/2. 100. 0. |

– 2δ(n-1) – 2 δ(n-2) + δ (n-3) +δ (n-4) δ(n-1) – 2 δ(n-2) – 2 δ (n-3) – δ (n-4) -2δ(n) – δ(n-1) – δ (n-2) + + δ(n-3) δ(n-1) + 2 δ(n-2) + δ(n-3) +2 δ (n-4) |

2U(n) -4 U(n-1) + 3 U(n-2) 2U(n) -4 U(n-1) + 3 U(n-2) – U(n-3) -2U(n) +4 U(n-1) + 3 U(n-2) – 3U(n-3) 2U(n) + 4 U(n-1) + 3 U(n-2) – 3U(n-3) |

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