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If f(x) = 3x^2 -4 and g(x) = 2x -1, what is (f of g)(x)?

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rosey-girl | Student, Grade 12 | Valedictorian

Posted May 20, 2013 at 10:39 PM via web

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If f(x) = 3x^2 -4 and g(x) = 2x -1, what is (f of g)(x)?

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crmhaske | College Teacher | (Level 3) Associate Educator

Posted May 20, 2013 at 10:43 PM (Answer #1)

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(f of g)(x)=f(g(x))

`f(g(x))=3(2x-1)^2-4`

`=3(4x^2-4x+1)-4`

`=12x^2-12x+3-1`

`=12x^2-12x+2`

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crmhaske | College Teacher | (Level 3) Associate Educator

Posted May 21, 2013 at 6:20 AM (Reply #1)

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`12z^2-12x+3-4`

`12x^2-12x-1`

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pramodpandey | College Teacher | Valedictorian

Posted May 21, 2013 at 6:12 AM (Answer #2)

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We have given

`f(x)=3x^2-4 `   and `g(x)=2x-1` ,We wish to find  `fog(x)`

`fog(x)=f(g(x))`

`=f(2x-1)=3(2x-1)^2-4`

`=3(4x^2-4x+1)-4`

`=12x^2-12x+3-4`

`=12x^2-12x-1`

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