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If `f,g: R -R` are defined respectively by `f(x)=x^2+3x+1,g(x)=2x-3,` find fog (ii) gof (iii) fof (iv) gog.

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`f(x) = x^2+3x+1, g(x) = 2x-3`
(i) `fog = f(g(x)) = f(2x-3) = (2x-3)^2+3(2x-3)+1`
`=4x^2+9-12x+6x-9+1`
`:. fog = 4x^2 -6x+1`
(ii) `gof = g(f(x)) = g( x^2+3x+1) = 2( x^2+3x+1) - 3 `
`=2x^2+6x+2-3`
`:.gof = 2x^2+6x-1`
...
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