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Gujarati JEE Mathematics : ગણ, સંબંધ અને વિધેય

Multiple Choice Questions

21.
f : (- ∞, 64) → R, f(x) = -square root of bold 64 bold space bold minus bold space bold x end root તથા g : [0, 2square root of bold 2 bold right square bracket bold space bold rightwards arrow bold space bold R bold comma bold space bold g bold left parenthesis bold x bold right parenthesis bold space bold equals bold space bold 8 bold x to the power of bold 2 હોય, તો સંયોજિત વિધેય નો મહત્તમ પ્રદેશ ......તેમજ વિસ્તાર ......... મળે.

bold left square bracket bold minus bold 2 square root of bold 2 bold comma bold space bold 2 square root of bold 2 bold right square bracket bold comma bold space bold left square bracket bold minus bold 8 bold comma bold space bold 0 bold right square bracket
  • bold left parenthesis bold minus bold 2 square root of bold 2 bold comma bold 2 square root of bold 2 bold right parenthesis bold left parenthesis bold 8 bold comma bold space bold 0 bold right parenthesis
  • bold left square bracket bold 0 bold comma bold space bold 2 square root of bold 2 bold right square bracket bold comma bold space bold left parenthesis bold minus bold 8 bold comma bold space bold 0 bold right parenthesis bold space
  • bold minus bold 2 square root of bold 2 bold comma bold space bold 2 square root of bold 2 bold right parenthesis bold comma bold space bold left parenthesis bold 0 bold comma bold space bold 8 bold right parenthesis

22. જો bold e to the power of bold f bold left parenthesis bold x bold right parenthesis end exponent bold space bold equals bold space fraction numerator bold 10 bold plus bold x over denominator bold 10 bold minus bold x end fraction bold apostrophe bold space bold e bold element of bold space bold left parenthesis bold minus bold 10 bold comma bold space bold 10 bold right parenthesis તથા f(x) = kf open parentheses fraction numerator bold 200 bold space bold x over denominator bold 100 bold space bold plus bold space bold x to the power of bold 2 end fraction close parentheses હોય, તો k = ...... .
  • 1 half
  • 3 over 5
  • 7 over 10
  • 4 over 5

23. bold f bold space bold colon bold space bold R bold space bold rightwards arrow bold space bold R bold comma bold space bold f bold left parenthesis bold x bold right parenthesis bold space bold equals bold space fraction numerator bold x bold space bold minus bold space bold left square bracket bold x bold right square bracket over denominator bold 1 bold space bold plus bold space bold x bold space bold minus bold space bold left square bracket bold x bold right square bracket end fraction હોય, તો bold f bold left parenthesis bold x bold right parenthesis bold space bold element of ......  જ્યાં [x] = પૂર્ણાંક ભાગ વિધેય.
  • open square brackets 0 comma 1 half close square brackets
  • left parenthesis 0 comma 1 half right square bracket
  • આપેલ પૈકી એક પણ નહી 


24. ધારો કે f(x) = fraction numerator bold 9 to the power of bold x over denominator bold 9 to the power of bold x bold space bold plus bold space bold 3 end fraction bold comma bold space bold x bold space bold element of bold space bold Rથી વિધેય વ્યાખ્યાયિત હોય, તો
bold f bold space open parentheses bold 1 over bold 2017 close parentheses bold space bold plus bold space bold f open parentheses bold 2 over bold 2017 close parentheses bold space bold plus bold space bold f bold space open parentheses bold 3 over bold 2017 close parentheses bold space bold plus bold space bold. bold. bold. bold space bold plus bold space bold f open parentheses bold 2016 over bold 2017 close parentheses bold space bold equals bold space bold. bold. bold. bold. bold. bold. bold. bold. bold. bold. bold space
  • 504

  • 4032

  • 2016

  • 1008


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25. bold f bold colon bold R bold space bold rightwards arrow bold space bold R bold comma bold space bold f bold left parenthesis bold x bold right parenthesis bold space bold equals bold space fraction numerator bold e to the power of bold vertical line bold x bold vertical line end exponent bold minus bold x to the power of bold minus bold x end exponent over denominator bold e to the power of bold e bold plus bold e to the power of bold minus bold x end exponent end fraction
  • એક-એક અને વ્યાપ્ત વિધેય છે. 

  • એક-એક વિધેય છે, પરંતુ વ્યાપ્ત વિધેય નથી. 

  • એક-એક વિધેય નથી, પરંતુ વ્યાપ્ત વિધેય છે. 

  • એક-એક પણ નથી તથા વ્યાપ્ત વિધેય નથી.


D.

એક-એક પણ નથી તથા વ્યાપ્ત વિધેય નથી.

Tips: -

અહીં bold f bold left parenthesis bold minus bold 1 bold right parenthesis bold space bold equals bold space fraction numerator bold e bold minus bold e to the power of bold minus bold left parenthesis bold minus bold 1 bold right parenthesis end exponent over denominator bold e to the power of bold minus bold 1 end exponent bold plus bold e end fraction bold space bold equals bold space fraction numerator bold e bold minus bold e over denominator bold e bold plus bold 1 over bold e end fraction bold space bold equals bold space bold 0 તથા bold f bold left parenthesis bold minus bold 2 bold right parenthesis bold space bold equals bold space fraction numerator bold e to the power of bold 2 bold space bold minus bold space bold e to the power of bold 2 over denominator bold e to the power of bold minus bold 2 end exponent bold plus bold e to the power of bold 2 end fraction bold space bold equals bold space bold 0

આમ,-1 ≠ -2  પરંતુ f(-1) = f(-2),  આથી એક-એક વિધેય નથી.

હવે,x>0 લેતાં, f(x) = fraction numerator bold e to the power of bold x bold minus bold e to the power of bold minus bold x end exponent over denominator bold e to the power of bold x bold plus bold e to the power of bold minus bold x end exponent end fraction મળે.
જો f(x) = 1  લઈએ, તો (i) c > 0 ⇒ ex - e-x = ex + e-x

∴ 2ex = 0 મળે, જે શક્ત નથી.

(iii)  x < 0 ⇒ e-x -ex + e-x પરથી, ex + e-x = 0 જે શક્ય નથી

∴ f(x) ≠ 1

આમ, વિસ્તાર R ન હોવાથી વિધેય f વ્યાપ્ત વિધેય નથી.


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26. f:R →R, f(x) = x-1 હોય તો { f-1 (-2)} ∪ {f-1 (17) } = ...... 
  • {-1, 18}

  • {0}

  • {±2(3)}

  • 0


27.
જો [x] એ મહત્તમ પૂર્ણાંક ભાગ વિધેય હોય અને [x] = x - [x] હોય, તો f(x) = [x] + bold sum from bold r bold space bold equals bold space bold 1 to bold 1000 of fraction numerator bold left curly bracket bold x bold space bold plus bold space bold r bold right curly bracket over denominator bold 1000 end fraction bold space bold equals bold space bold. bold. bold. bold. bold. bold. bold space bold. 
  • -x

  • x2

  • 1/x

  • x


28. bold f bold left parenthesis bold x bold right parenthesis bold space bold equals bold space fraction numerator bold e to the power of bold x bold space bold minus bold space bold e blank presuperscript bold minus bold x end presuperscript over denominator bold 2 end fraction તથા f(g(x)) = xહોય, તો g open parentheses fraction numerator bold e to the power of bold 2016 bold minus bold 1 over denominator bold 2 bold e to the power of bold 1008 end fraction close parentheses bold space bold equals bold space bold. bold. bold. bold. bold. bold. bold. bold. bold. bold. bold. bold. bold.
  • 2016

  • 252

  • 1008

  • 504


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29. જો f(x) = bold left parenthesis bold a bold minus bold x to the power of bold n bold right parenthesis to the power of begin inline style bold 1 over bold n end style end exponent bold comma bold space bold x bold space bold greater than bold space bold 0 હોય, તો bold f bold space bold left parenthesis bold f bold left parenthesis bold x bold right parenthesis bold right parenthesis bold space bold plus bold space bold f bold space open parentheses bold f open parentheses bold 1 over bold x close parentheses bold space close parentheses ............ મળે.   x > 0
  • < 2

  • ≥2

  • 0≥0

  • =10


30. વિધેય f:A→(1, ∞); f(x) = 1 + x3 એ એક-એક વિધેય હોય, તો A =  ......... શક્ય બને. 
  • [1, ∞]

  • R+

  • R

  • [0, ∞]


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