Sunday, January 8, 2012

Whats your function?

(f + g)(x) – add equations


(f – g)(x) – subtract equations


(f ●g)(x) – multiply


(f/g)(x) – divide


(f ᵒ g)(x) or f(g(x)) – replace all x’s in the f(x) equation with the equation g(x)


Your answer should be in factored form if possible


If x is replaced with a number, plug into the equation



Ex 1: f(x) = x + 1 and g(x) = x^2 – 1 Find the rule for a. (f + g) (x) b. (f/g) (x) c. (f ● g) (x)



a. (x + 1) + (x^2 – 1)


x^2 + x


x (x + 1)



b. x + 1/x^2 – 1


x + 1/(x + 1) (x – 1)


1/(x – 1)



c. (x+1) (x^2 – 1)


(x+1)^2 (x – 1)



Ex 2: f(x) = x^4 – 3x^3 and g(x) = x – 2 Find (f ᵒ g) (x)



f (g(x)) = (x – 2)^4 – 3(x– 2)^3


(x –2)^3((x –2) – 3)


(x – 2)^3 (x – 5)



Ex 3: f(x) = 1/x and g(x) = x + 2 Find (f ᵒ g) (x) and (g ᵒ f) (x)



f(g(x)) = 1/(x + 2)


g(f(x)) = (1/x) + 2

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