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Given that f(x)=11, g(x)=x^2-6x+3, and h(x)= -x+4, find the function (g •h)(x).

User Winter Dragoness
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1 Answer

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16 votes

Answer:


(g \cdot h)(x)=x^2-2x+23

Explanation:

For composite functions, it's important to understand what the functions mean:


(g\cdot h)(x) which is read as "g of h, of x" means
g ( \text{ }h(x) \text{ }) which is read as "g of, h of x" (with slight pauses at the comma). This means that x goes into the h function, and the output of the h function goes into the g function.

Putting "x" into the h function


h(x)=-x+4

Since it is just "x" going into the h function, the function as written is the output when x is the input.

Putting the h function output, into the g function


g(x)=x^2-6x+3


g(h(x))=(h(x))^2-6(h(x))+3

Substitute


g(h(x))=(-x+4)^2+-6(-x+4)+3

Squaring means the something multiplied by itself


g(h(x))=(-x+4)*(-x+4)+-6(-x+4)+3

Use distributive property; (some people know binomial distribution as "FOIL" -- First, Outer, Inner, Last):


g(h(x))=[(-x)(-x)+4(-x)+4(-x)+4*4)]+[6x+4]+3

Simplify the binomial terms:


g(h(x))=[x^2-8x+16]+[6x+4]+3

Group like terms:


g(h(x))=x^2-2x+23

Remember that
(g\cdot h)(x) means
g ( \text{ }h(x) \text{ })


(g \cdot h)(x)=x^2-2x+23

So,
(g \cdot h)(x)=x^2-2x+23

User Stav
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