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Calculating a quartic polynomial by squaring a quadratic expression of the form $ax^2+bx+c$.

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Given a function \\[ f(x) = \\simplify{{a}x^2+{b}x+{c}},\\]

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calculate \\[ \\left[ f(x) \\right]^2 .\\]

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 When calculating $\\left[f(x)\\right]^2$, it is important to remember that this means we are multiplying the entire function by itself, and not simply squaring each term.

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So,

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\\[ \\begin{split} \\left[f(x)\\right]^2 &\\,= (\\simplify{{a}x^2+{b}x+{c}})(\\simplify{{a}x^2+{b}x+{c}}) \\\\ &\\,= \\simplify{{a}x^2 ({a}x^2+{b}x+{c}) +{b}x({a}x^2+{b}x+{c})+{c}({a}x^2+{b}x+{c})} \\end{split} \\]

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Multiplying out the brackets and collecting similar terms:

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\\[ \\begin{split} \\left[f(x)\\right]^2 &\\,= \\simplify{{a}x^2 ({a}x^2+{b}x+{c}) +{b}x({a}x^2+{b}x+{c})+{c}({a}x^2+{b}x+{c})} \\\\ &\\,= \\simplify[all,!cancelTerms, !collectNumbers]{{a^2}x^4+{a*b}x^3+{a*c}x^2+{b*a}x^3+{b^2}x^2+{b*c}x+{c*a}x^2+{c*b}x+{c^2}}\\\\ &\\,= \\simplify{{a^2}x^4+{a*b}x^3+{a*c}x^2+{b*a}x^3+{b^2}x^2+{b*c}x+{c*a}x^2+{c*b}x+{c^2}}\\end{split} \\]

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