Let ƒ(x)=2x-3 and g(x)=-x+3. Find each function value. See Example 5.
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Understand that the notation \((ƒ \circ g)(-2)\) means the composition of functions \(ƒ\) and \(g\) evaluated at \(-2\). This is written as \(ƒ(g(-2))\), which means you first find \(g(-2)\) and then plug that result into \(ƒ\).
Calculate \(g(-2)\) by substituting \(x = -2\) into the function \(g(x) = -x + 3\). So, \(g(-2) = -(-2) + 3\).
Simplify the expression for \(g(-2)\) to find its value. This will give you the input to use in the next step.
Next, substitute the value you found for \(g(-2)\) into the function \(ƒ(x) = 2x - 3\). So, calculate \(ƒ(g(-2)) = 2 \times g(-2) - 3\).
Simplify the expression for \(ƒ(g(-2))\) to find the final value of the composition \((ƒ \circ g)(-2)\).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Function Composition
Function composition involves applying one function to the result of another, denoted as (f∘g)(x) = f(g(x)). To evaluate (f∘g)(-2), first find g(-2), then substitute that value into f. This process combines two functions into a single operation.
Evaluating a function means substituting a specific input value into the function's formula and simplifying to find the output. For example, to find g(-2), replace x with -2 in g(x) = -x + 3 and simplify.
Linear functions have the form f(x) = mx + b, where m and b are constants. Both f(x) = 2x - 3 and g(x) = -x + 3 are linear, meaning their graphs are straight lines and their outputs change at a constant rate with respect to x.