// Numbas version: finer_feedback_settings {"name": "Polynomials: Expand and Simplify 2d", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Polynomials: Expand and Simplify 2d", "tags": [], "metadata": {"description": "
Finding the product of a linear function of the form $mx+c$ and a cubic function of the form $ax^3+bx^2+cx+d$.
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\n\\[ (\\simplify{{c2}x+{d2}})(\\simplify{{a1}x^3+{b1}x^2+{c1}x+{d1}})\\]
", "advice": "To expand and simplify
\n\\[ (\\simplify{{c2}x+{d2}})(\\simplify{{a1}x^3+{b1}x^2+{c1}x+{d1}}),\\]
\nwe will first multiply the cubic polynomial by each term in the first bracket:
\n\\[ (\\simplify{{c2}x+{d2}})(\\simplify{{a1}x^3+{b1}x^2+{c1}x+{d1}}) = \\simplify{{c2}x ({a1}x^3+{b1}x^2+{c1}x+{d1})+{d2}({a1}x^3+{b1}x^2+{c1}x+{d1})}.\\]
\nWe can now expand each bracket and collect similar terms to simplify:
\n\\[ \\begin{split} (\\simplify{{c2}x+{d2}})(\\simplify{{a1}x^3+{b1}x^2+{c1}x+{d1}}) &\\,= \\simplify{{c2}x ({a1}x^3+{b1}x^2+{c1}x+{d1})+{d2}({a1}x^3+{b1}x^2+{c1}x+{d1})} \\\\ &\\,= \\simplify[all,!collectNumbers, !cancelTerms]{{c2*a1}x^4+{c2*b1}x^3+{c2*c1}x^2+{c2*d1}x +{d2*a1}x^3+{d2*b1}x^2+{d2*c1}x+{d2*d1}} \\\\ &\\,= \\simplify{{c2*a1}x^4+{c2*b1}x^3+{c2*c1}x^2+{c2*d1}x +{d2*a1}x^3+{d2*b1}x^2+{d2*c1}x+{d2*d1}} \\end{split}\\]
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