// Numbas version: exam_results_page_options {"name": "Copy of Q2 Adding and subtracting surds", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Copy of Q2 Adding and subtracting surds", "tags": [], "metadata": {"description": "
Adding and subtracting surds. Parts b) and c) involve simplification of surds.
", "licence": "Creative Commons Attribution 4.0 International"}, "statement": "To include a square root sign in your answer use sqrt()
. For example, to write $\\sqrt{3}$, type sqrt(3)
into the answer box. If you are entering a number multiplied by the square root of some other number, for example $3\\sqrt{5}$, type 3sqrt(5)
into the answer box.
a)
\nSimplify $\\simplify[!cancelTerms]{{d}sqrt({a}) - sqrt({a})+{n}sqrt({a})}$.
\nThe surds are all like surds, so we can collect like surds.
\n$\\simplify[!cancelTerms]{{d}sqrt({a}) - sqrt({a})+{n}sqrt({a})={d-1+n}sqrt({a})}$.
\n\nb)
\n$\\simplify[!cancelTerms]{{d}sqrt({a}) + sqrt({v^2*a})-sqrt({b^2*a})}$
\nLook for factors of the surds which are square numbers ( $4, 9, 16, 25, 36, 49, 64, 81, 100, ... $).
\nIn this question the second term has a square factor $\\var{v^2}$ and the third term has a square factor $\\var{b^2}$.
\n\\[
\\begin{align}
\\simplify[!cancelTerms]{{d}sqrt({a}) + sqrt({v^2*a})-sqrt({b^2*a})} &= \\var{d}\\sqrt{\\var{a}} + (\\sqrt{\\simplify{{v}^2}} \\times \\sqrt{\\var{a}})-(\\sqrt{\\simplify{{b}^2}} \\times \\sqrt{\\var{a}}) \\\\
&= \\var{d}\\sqrt{\\var{a}} +\\var{v}\\sqrt{\\var{a}}-\\var{b}\\sqrt{\\var{a}} \\\\
&= \\simplify{({d}+{v}-{b})sqrt({a})} \\text{.}
\\end{align}
\\]
c)
\n\\[
\\begin{align}
\\simplify{{d}sqrt({a}) - {b}sqrt({v}^2{a})+{n}sqrt({b}^2*{a})} &= \\var{d}\\sqrt{\\var{a}} - \\var{b}(\\sqrt{\\simplify{{v}^2}} \\times \\sqrt{\\var{a}})+\\var{n}(\\sqrt{\\simplify{{b}^2}} \\times \\sqrt{\\var{a}}) \\\\
&= \\var{d}\\sqrt{\\var{a}} -\\var{b}(\\simplify{{v}*sqrt({a})})+\\var{n}(\\simplify{{b}*sqrt({a})}) \\\\
&= \\simplify{{d}sqrt({a})}-\\simplify{{b}*{v}sqrt({a})}+\\simplify{{n}*{b}sqrt({a})} \\\\
&= \\simplify{({d}-{b}*{v}+{n}*{b})sqrt({a})} \\text{.}
\\end{align}
\\]
Simplify $\\simplify[!cancelTerms]{{d}sqrt({a}) - sqrt({a})+{n}sqrt({a})}$.
\n$\\simplify[!cancelTerms]{{d}sqrt({a}) - sqrt({a})+{n}sqrt({a})}$ = [[0]].
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\n$\\simplify[!cancelTerms]{{d}sqrt({a}) + sqrt({v^2*a})-sqrt({b^2*a})}$= [[0]].
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\n$\\simplify{{d}sqrt({a}) - {b}sqrt({v}^2*{a})+{n}sqrt({b}^2*{a})} =$ [[0]].
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