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Differentiate $\\displaystyle e^{ax^{m} +bx^2+c}$
", "licence": "Creative Commons Attribution 4.0 International"}, "parts": [{"showCorrectAnswer": true, "showFeedbackIcon": true, "prompt": "\\[\\simplify[std]{f(x) = e^({a}x^{m} +{b}x^2+{c})}\\]
\n$\\displaystyle \\frac{df}{dx}=\\;$[[0]]
", "type": "gapfill", "gaps": [{"showCorrectAnswer": true, "answer": "({m*a}x^{m-1}+{2*b}x)*e^({a}x^{m} +{b}x^2+{c})", "showpreview": true, "marks": 3, "scripts": {}, "vsetrange": [0, 1], "variableReplacementStrategy": "originalfirst", "expectedvariablenames": [], "showFeedbackIcon": false, "type": "jme", "checkingtype": "absdiff", "answersimplification": "std", "checkingaccuracy": 0.001, "vsetrangepoints": 5, "checkvariablenames": false, "variableReplacements": []}], "marks": 0, "scripts": {}, "variableReplacementStrategy": "originalfirst", "variableReplacements": []}], "rulesets": {"std": ["all", "!collectNumbers", "fractionNumbers"]}, "statement": "Differentiate the following function $f(x)$ using the chain rule.
", "functions": {}, "advice": "\n\t \n\t \n\t$\\simplify[std]{f(x) = e^({a}x^{m} +{b}x^2+{c})}$
The chain rule says that if $f(x)=g(h(x))$ then
\\[\\simplify[std]{f'(x) = h'(x)g'(h(x))}\\]
One way to find $f'(x)$ is to let $u=h(x)$ then we have $f(u)=g(u)$ as a function of $u$.
Then we use the chain rule in the form:
\\[\\frac{df}{dx} = \\frac{du}{dx}\\frac{df(u)}{du}\\]
Once you have worked this out, you replace $u$ by $h(x)$ and your answer is now in terms of $x$.
For this example, we let $u=\\simplify[std]{{a}x^{m} +{b}x^2+{c}}$ and we have $f(u)=\\simplify[std]{e^u}$.
This gives
\\[\\begin{eqnarray*}\\frac{du}{dx} &=& \\simplify[std]{{a*m}x^{m-1} +{2*b}x}\\\\\n\t \n\t \\frac{df(u)}{du} &=& \\simplify[std]{e^u} \\end{eqnarray*}\\]
Hence on substituting into the chain rule above we get:
\n\t \n\t \n\t \n\t\\[\\begin{eqnarray*}\\frac{df}{dx} &=& \\simplify[std]{({a*m}x^{m-1} +{2*b}x) * (e^u)}\\\\\n\t \n\t &=& \\simplify[std]{({a*m}x^{m-1} +{2*b}x)*e^({a}x^{m} +{b}x^2+{c})}\n\t \n\t \\end{eqnarray*}\\]
on replacing $u$ by $\\simplify[std]{{a}x^{m} +{b}x^2+{c}}$.