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Kreshnik

  • 4 years ago

\[\LARGE f'(x)=x^2+3x \;\; ,\;\; f(1)=5\;\;\;\;\Longrightarrow f(2)=?\] I need some hints

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  1. SUROJ
    • 4 years ago
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    f(x) can be obtained by integration........then use f(1) to find value of c, then find f(2)

  2. Rohangrr
    • 4 years ago
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    ya suroj ur correctt

  3. SUROJ
    • 4 years ago
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    got it?

  4. Kreshnik
    • 4 years ago
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    \[\LARGE f(x)=\frac13 x^3 +\frac32 x^2 \;\;\;\;??\]

  5. SUROJ
    • 4 years ago
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    you left +C at the end

  6. SUROJ
    • 4 years ago
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    you need to add +C at end because it is integration

  7. SUROJ
    • 4 years ago
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    indefinite integration

  8. Kreshnik
    • 4 years ago
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    ok but... I need to firnd f(2) then how??

  9. SUROJ
    • 4 years ago
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    on the second condition when x=1, y=5, you see , put those values and get c

  10. Kreshnik
    • 4 years ago
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    \[\LARGE \int\limits x^2+3x \;dx = \frac13 x^3+\frac32x^2+C\]

  11. SUROJ
    • 4 years ago
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    put the c back on f(x) and get complete f(x) equation and then find f(2)

  12. SUROJ
    • 4 years ago
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    yes

  13. Rohangrr
    • 4 years ago
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    correct

  14. Kreshnik
    • 4 years ago
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    how can I know what the value of C is ??

  15. Kreshnik
    • 4 years ago
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    I see it you told me before... let me try, I'll see what I can do :D

  16. SUROJ
    • 4 years ago
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    see second condition f(1) is 5 than mean when x=1 , y=5

  17. SUROJ
    • 4 years ago
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    see f(x) is what you get by integration

  18. SUROJ
    • 4 years ago
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    because you integrate f'(x)

  19. SUROJ
    • 4 years ago
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    did you catch it?

  20. Kreshnik
    • 4 years ago
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    is C=19/6 ??

  21. Kreshnik
    • 4 years ago
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    I'm still dizzy ! O_O

  22. SUROJ
    • 4 years ago
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    yes you got it

  23. SUROJ
    • 4 years ago
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    now put that C back in f(x)

  24. SUROJ
    • 4 years ago
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    got it?

  25. Kreshnik
    • 4 years ago
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    ahh yeah... now I'll do it thank you very much ;)

  26. SUROJ
    • 4 years ago
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    no problem lol

  27. JoshDavoll
    • 4 years ago
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    \[f \left( x \right) = x ^{2} + 3x\] \[f \left( 1 \right) = 1^{2} + 3 \times 1 = 5\] \[f \left( 2 \right) = 2^{2} + 3 \times 2 = 10\] simple.

  28. JoshDavoll
    • 4 years ago
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    @kreshnik another simple way to do something.

  29. Kreshnik
    • 4 years ago
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    @JoshDavoll WRONG... the answer IS \[\frac{71}{6}\] !! Thanks for the help !

  30. Kreshnik
    • 4 years ago
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    hahaha... obviously , you mus be 10-12 years ... LOL

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