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Functions $f$ and $g$ are defined on suitable domains by $f(x) = 5x$ and $g(x) = 2 ext{cos} \, x$ - Scottish Highers Maths - Question 1 - 2017

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Question 1

Functions-$f$-and-$g$-are-defined-on-suitable-domains-by-$f(x)-=-5x$-and-$g(x)-=-2-ext{cos}-\,-x$-Scottish Highers Maths-Question 1-2017.png

Functions $f$ and $g$ are defined on suitable domains by $f(x) = 5x$ and $g(x) = 2 ext{cos} \, x$. (a) Evaluate $f(g(0))$. (b) Find an expression for $g(f(x))$.

Worked Solution & Example Answer:Functions $f$ and $g$ are defined on suitable domains by $f(x) = 5x$ and $g(x) = 2 ext{cos} \, x$ - Scottish Highers Maths - Question 1 - 2017

Step 1

Evaluate $f(g(0))$

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Answer

To evaluate f(g(0))f(g(0)), we first need to find g(0)g(0).

Given:

g(x) = 2 ext{cos} , x,

we substitute 0 into the function:

g(0)=2extcos(0)=2(1)=2.g(0) = 2 ext{cos}(0) = 2(1) = 2.

Now that we have g(0)=2g(0) = 2, we can substitute this value into the function ff:

f(g(0))=f(2)=5(2)=10.f(g(0)) = f(2) = 5(2) = 10.

Therefore, the answer is:

$$f(g(0)) = 10.$

Step 2

Find an expression for $g(f(x))$

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Answer

To find the expression for g(f(x))g(f(x)), we start with the function definitions:

f(x)=5xf(x) = 5x and g(x)=2extcosx.g(x) = 2 ext{cos} \, x.

Now we need to substitute f(x)f(x) into g(x)g(x):

g(f(x))=g(5x)=2extcos(5x).g(f(x)) = g(5x) = 2 ext{cos}(5x).

Thus, the expression for g(f(x))g(f(x)) is:

g(f(x))=2extcos(5x).g(f(x)) = 2 ext{cos}(5x).

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