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When multiplying matrices you must do it such that:

\n

$A=\\left (\\begin{matrix}a & b & c \\\\ d&e&f\\end{matrix} \\right) \\; \\; \\;B=\\left(\\begin{matrix}  g\\\\ h \\\\ i\\end{matrix}\\right)$

\n

$\\Rightarrow \\; AB=\\left(\\begin{matrix}ag+bh+ci \\\\ dg+eh+fi \\end{matrix}\\right)$

\n

Therefore:

\n

$Av=\\left(\\begin{matrix} \\var{a11*v1}+\\var{a12*v2}+\\var{a13*v3} \\\\ \\var{a21*v1}+\\var{a22*v2}+\\var{a23*v3} \\\\ \\var{a31*v1}+\\var{a32*v2}+\\var{a33*v3} \\end{matrix} \\right)$

\n

$\\Rightarrow \\left(\\begin{matrix} \\simplify{{a11*v1}+{a12*v2}+{a13*v3}} \\\\ \\simplify{{a21*v1}+{a22*v2}+{a23*v3}} \\\\ \\simplify{{a31*v1}+{a32*v2}+{a33*v3}} \\end{matrix} \\right)$

\n

$\\\\ $

\n

$Bw=\\left(\\begin{matrix} \\var{b11*w1}+\\var{b12*w2}+\\var{b13*w3} \\\\ \\var{b21*w1}+\\var{b22*w2}+\\var{b23*w3} \\\\ \\var{b31*w1}+\\var{b32*w2}+\\var{b33*w3} \\end{matrix} \\right)$

\n

$\\Rightarrow \\left(\\begin{matrix} \\simplify{{b11*w1}+{b12*w2}+{b13*w3}} \\\\ \\simplify{{b21*w1}+{b22*w2}+{b23*w3}} \\\\ \\simplify{{b31*w1}+{b32*w2}+{b33*w3}} \\end{matrix} \\right)$

\n

$\\\\ $

\n

$BA=\\left(\\begin{matrix} \\var{b11*a11}+\\var{b12*a21}+\\var{b13*a31} & \\var{b11*a12}+\\var{b12 a22}+\\var{b13 a32} & \\var{b11 a13}+\\var{b12 a23}+\\var{b13 a33} \\\\ \\var{b21*a11}+\\var{b22*a21}+\\var{b23*a31} & \\var{b21*a12}+\\var{b22 a22}+\\var{b23 a32} & \\var{b21 a13}+\\var{b22 a23}+\\var{b23 a33} \\\\ \\var{b31*a11}+\\var{b32*a21}+\\var{b33*a31} & \\var{b31*a12}+\\var{b32 a22}+\\var{b33 a32} & \\var{b31 a13}+\\var{b32 a23}+\\var{b33 a33}   \\end{matrix}\\right)$

\n

$\\Rightarrow \\left(\\begin{matrix} \\simplify{{b11*a11}+{b12*a21}+{b13*a31}} & \\simplify{{b11*a12}+{b12 a22}+{b13 a32}} & \\simplify{{b11 a13}+{b12 a23}+{b13 a33}} \\\\ \\simplify{{b21*a11}+{b22*a21}+{b23*a31}} & \\simplify{{b21*a12}+{b22 a22}+{b23 a32}} & \\simplify{{b21 a13}+{b22 a23}+{b23 a33}} \\\\ \\simplify{{b31*a11}+{b32*a21}+{b33*a31}} & \\simplify{{b31*a12}+{b32 a22}+{b33 a32}} & \\simplify{{b31 a13}+{b32 a23}+{b33 a33}}   \\end{matrix}\\right)$

\n

$\\\\ $

\n

$AB=\\left(\\begin{matrix} \\var{a11*b11}+\\var{a12*b21}+\\var{a13*b31} & \\var{a11*b12}+\\var{a12 b22}+\\var{a13 b32} & \\var{a11 b13}+\\var{a12 b23}+\\var{a13 b33} \\\\ \\var{a21*b11}+\\var{a22*b21}+\\var{a23*b31} & \\var{a21*b12}+\\var{a22 b22}+\\var{a23 b32} & \\var{a21 b13}+\\var{a22 b23}+\\var{a23 b33} \\\\ \\var{a31*b11}+\\var{a32*b21}+\\var{a33*b31} & \\var{a31*b12}+\\var{a32 b22}+\\var{a33 b32} & \\var{a31 b13}+\\var{a32 b23}+\\var{a33 b33}   \\end{matrix}\\right)$

\n

$\\Rightarrow \\left(\\begin{matrix} \\simplify{{a11*b11}+{a12*b21}+{a13*b31}} & \\simplify{{a11*b12}+{a12 b22}+{a13 b32}} & \\simplify{{a11 b13}+{a12 b23}+{a13 b33}} \\\\ \\simplify{{a21*b11}+{a22*b21}+{a23*b31}} & \\simplify{{a21*b12}+{a22 b22}+{a23 b32}} & \\simplify{{a21 b13}+{a22 b23}+{a23 b33}} \\\\ \\simplify{{a31*b11}+{a32*b21}+{a33*b31}} & \\simplify{{a31*b12}+{a32 b22}+{a33 b32}} & \\simplify{{a31 b13}+{a32 b23}+{a33 b33}}   \\end{matrix}\\right)$

\n

", "rulesets": {"std": ["all", "!collectNumbers", "fractionNumbers", "!noLeadingMinus"]}, "parts": [{"prompt": "

Let

\n

\\[A = \\left(\\begin{array}{rrr} \\var{a11} & \\var{a12} & \\var{a13}\\\\ \\var{a21} & \\var{a22} & \\var{a23}\\\\ \\var{a31} & \\var{a32} & \\var{a33}\\\\ \\end{array}\\right),\\;\\;\\;\\; B= \\left(\\begin{array}{rrr} \\var{b11} & \\var{b12} & \\var{b13}\\\\ \\var{b21} & \\var{b22} & \\var{b23}\\\\ \\var{b31} & \\var{b32} & \\var{b33}\\\\ \\end{array}\\right),\\;\\;\\;\\; v= \\left(\\begin{array}{r} \\var{v1}\\\\ \\var{v2} \\\\ \\var{v3} \\end{array}\\right),\\;\\;\\;\\; w= \\left(\\begin{array}{r} \\var{w1}\\\\ \\var{w2} \\\\ \\var{w3} \\end{array}\\right)\\]

\n

Find the following products:

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\\[ Av=\\left( \\begin{matrix} \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\end{matrix} \\right.\\][[0]]\\[\\left) \\begin{matrix} \\phantom{.} \\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\end{matrix} \\right.\\]
[[1]]
[[2]]
\\[ Bw=\\left( \\begin{matrix} \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\end{matrix} \\right.\\][[3]]\\[\\left) \\begin{matrix} \\phantom{.} \\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\end{matrix} \\right.\\]
[[4]]
[[5]]
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\\[BA=\\left( \\begin{matrix} \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\end{matrix} \\right.\\][[6]][[7]][[8]]\\[\\left) \\begin{matrix} \\phantom{.} \\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\end{matrix} \\right.\\]
[[9]][[10]][[11]]
[[12]][[13]][[14]]
\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\\[AB=\\left( \\begin{matrix} \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\end{matrix} \\right.\\][[15]][[16]][[17]]\\[\\left) \\begin{matrix} \\phantom{.} \\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\phantom{.}\\\\ \\end{matrix} \\right.\\]
[[18]][[19]][[20]]
[[21]][[22]][[23]]
\n

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{}, "marks": 0.5, "type": "numberentry", "correctAnswerStyle": "plain"}, {"allowFractions": false, "variableReplacements": [], "maxValue": "{ab31}", "minValue": "{ab31}", "variableReplacementStrategy": "originalfirst", "notationStyles": ["plain", "en", "si-en"], "correctAnswerFraction": false, "showCorrectAnswer": true, "scripts": {}, "marks": 0.5, "type": "numberentry", "correctAnswerStyle": "plain"}, {"allowFractions": false, "variableReplacements": [], "maxValue": "{ab32}", "minValue": "{ab32}", "variableReplacementStrategy": "originalfirst", "notationStyles": ["plain", "en", "si-en"], "correctAnswerFraction": false, "showCorrectAnswer": true, "scripts": {}, "marks": 0.5, "type": "numberentry", "correctAnswerStyle": "plain"}, {"allowFractions": false, "variableReplacements": [], "maxValue": "{ab33}", "minValue": "{ab33}", "variableReplacementStrategy": "originalfirst", "notationStyles": ["plain", "en", "si-en"], "correctAnswerFraction": false, "showCorrectAnswer": true, "scripts": {}, "marks": 0.5, "type": "numberentry", "correctAnswerStyle": "plain"}], "showCorrectAnswer": true, "scripts": {}, "marks": 0, "type": "gapfill"}], "extensions": ["stats"], "statement": "

Answer the following questions on matrices.

\n

 

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"random(0,1)", "templateType": "anything", "group": "Ungrouped variables", "name": "b12", "description": ""}, "b13": {"definition": "random(-2..2)", "templateType": "anything", "group": "Ungrouped variables", "name": "b13", "description": ""}, "b11": {"definition": "random(0,1)", "templateType": "anything", "group": "Ungrouped variables", "name": "b11", "description": ""}, "c13": {"definition": "random(1..2)", "templateType": "anything", "group": "Ungrouped variables", "name": "c13", "description": ""}, "c12": {"definition": "random(1..3)", "templateType": "anything", "group": "Ungrouped variables", "name": "c12", "description": ""}, "c11": {"definition": "random(-2..2)", "templateType": "anything", "group": "Ungrouped variables", "name": "c11", "description": ""}, "a33": {"definition": "random(1..4)", "templateType": "anything", "group": "Ungrouped variables", "name": "a33", "description": ""}, "a32": {"definition": "random(-4..4)", "templateType": "anything", "group": "Ungrouped 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variables", "name": "mad", "description": ""}, "mag": {"definition": "matrix(repeat(repeat(random(-2..9),u),w))", "templateType": "anything", "group": "Ungrouped variables", "name": "mag", "description": ""}, "mah": {"definition": "matrix(repeat(repeat(random(-2..9),x),y))", "templateType": "anything", "group": "Ungrouped variables", "name": "mah", "description": ""}, "ba12": {"definition": "b11*a12+b12*a22+b13*a32", "templateType": "anything", "group": "Ungrouped variables", "name": "ba12", "description": ""}, "ba13": {"definition": "b11*a13+b12*a23+b13*a33", "templateType": "anything", "group": "Ungrouped variables", "name": "ba13", "description": ""}, "b33": {"definition": "random(-2..2)", "templateType": "anything", "group": "Ungrouped variables", "name": "b33", "description": ""}, "p2": {"definition": "a21*v1+a22*v2+a23*v3", "templateType": "anything", "group": "Ungrouped variables", "name": "p2", "description": ""}, "p3": {"definition": "a31*v1+a32*v2+a33*v3", "templateType": 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"templateType": "anything", "group": "Ungrouped variables", "name": "ab12", "description": ""}, "m": {"definition": "random(3..4)", "templateType": "anything", "group": "Ungrouped variables", "name": "m", "description": ""}, "v2": {"definition": "random(1..4)", "templateType": "anything", "group": "Ungrouped variables", "name": "v2", "description": ""}, "n": {"definition": "random(3..6 except m)", "templateType": "anything", "group": "Ungrouped variables", "name": "n", "description": ""}, "q": {"definition": "m+random(0,z)", "templateType": "anything", "group": "Ungrouped variables", "name": "q", "description": ""}, "p": {"definition": "n+random(0,z)", "templateType": "anything", "group": "Ungrouped variables", "name": "p", "description": ""}, "s": {"definition": "random(4..6)", "templateType": "anything", "group": "Ungrouped variables", "name": "s", "description": ""}, "r": {"definition": "random(1..3)", "templateType": "anything", "group": "Ungrouped variables", "name": "r", "description": ""}, "u": {"definition": "random(3..4)", "templateType": "anything", "group": "Ungrouped variables", "name": "u", "description": ""}, "w": {"definition": "random(3..5)", "templateType": "anything", "group": "Ungrouped variables", "name": "w", "description": ""}, "v": {"definition": "[[s1,-s1],[s2,-s2],[s3,-s3],[s4,-s4],[s5,-s5],[s6,-s6],[s7,-s7],[s8,-s8],[s9,-s9],[s10,-s10]]", "templateType": "anything", "group": "Ungrouped variables", "name": "v", "description": ""}, "y": {"definition": "u+random(0,z)", "templateType": "anything", "group": "Ungrouped variables", "name": "y", "description": ""}, "x": {"definition": "u+random(0,z)", "templateType": "anything", "group": "Ungrouped variables", "name": "x", "description": ""}, "z": {"definition": "random(-2,-1,1,2)", "templateType": "anything", "group": "Ungrouped variables", "name": "z", "description": ""}, "ab13": {"definition": "a11*b13+a12*b23+a13*b33", "templateType": "anything", "group": "Ungrouped variables", "name": "ab13", "description": ""}}, "metadata": {"description": "

Elementary Exercises in multiplying matrices. 

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