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Given f(x)=2x^2-5 and g(x)=4-2x, find (f of g)(x).

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rosey-girl | Student, Grade 12 | (Level 1) Valedictorian

Posted November 8, 2012 at 4:32 AM via web

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Given f(x)=2x^2-5 and g(x)=4-2x, find (f of g)(x).

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durbanville | High School Teacher | (Level 1) Educator Emeritus

Posted November 8, 2012 at 5:41 AM (Answer #1)

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`f(x) = 2x^2 - 5` and `g(x) = 4-2x` substitute g(x) for every value of x in f(x)

`therefore` (f of g)x can be written as:

f(g(x))=  `2(4-2x)^2 - 5`

= `2(16 - 16x + 4x^2) -5`

= `32- 32x +8x^2 -5`

= `8x^2 -32x + 27`

 

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