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Drewkatski

  • one year ago

Hi I don't understand how to go about this question. thanks in advance for help. The domains of these functions are the set of all positive real numbers, Find their ranges, 1. f(x)=2x+7 2. f(x)=x^2-1

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  1. Drewkatski
    • one year ago
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    @nincompoop

  2. alekos
    • one year ago
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    the domain is all the possible x values which in this case is x>0 the range is all the possible y values

  3. welshfella
    • one year ago
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    Note: number 2 - what sign is a square number?

  4. welshfella
    • one year ago
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    - if x is real can a square number ever be negative?

  5. welshfella
    • one year ago
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    In any case x>0 as alekos has said so what does that make the range of values of x^2?

  6. amoodarya
    • one year ago
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    \[x>0 \rightarrow 2x >0 \rightarrow 2x+7 >0+7\\x> 0 \rightarrow x^2 >0 \rightarrow x^2-1>0-1\]

  7. alekos
    • one year ago
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    Nice answer amoodarya

  8. Drewkatski
    • one year ago
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    Sorry I was afk, thanks to all for answering

  9. Drewkatski
    • one year ago
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    @amoodarya how do I apply this to one of the later questions: f(x) = (x+2)^2-1

  10. phi
    • one year ago
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    for f(x)=2x+7 if x>0 then f(x) will be bigger than 7 the range is y>7

  11. alekos
    • one year ago
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    with f(x) = (x+2)^2 -1 just apply the same procedure x>0 x+2>2 and so on until you get f(x) > ......

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