// Numbas version: exam_results_page_options {"name": "Complex Numbers; Multiplication 01 (Rect')", "extensions": [], "custom_part_types": [], "resources": [], "navigation": {"allowregen": true, "showfrontpage": false, "preventleave": false, "typeendtoleave": false}, "question_groups": [{"pickingStrategy": "all-ordered", "questions": [{"name": "Complex Numbers; Multiplication 01 (Rect')", "tags": [], "metadata": {"description": "Multiplication of complex numbers (in rectangular, Cartesian form)", "licence": "All rights reserved"}, "statement": "

Let $z$ and $w$ be any two complex numbers

\n

$   z=a+bi   $          and          $   w=c+di   $ 

\n

Then 

\n

$z w = (a + bi)(c + di)$

\n

$z w = ac-bd+(ad+bc)i$

", "advice": "

We are asked to evaluate the following multiplications of complex numbers.

\n

The technique should be very familiar. It is exactly the same as multiplying out two brackets.

\n

The workings below probably include more steps than really neccesary once you get used to doing it.

\n

Given:

\n

$\\large z_1=\\var{z1}$     and      $\\large z_2=\\var{z2}$

\n

\n

Evaluate:

\n

$\\large z_1z_2=(\\var{z1})(\\var{z2})$ 

\n

$\\large z_1z_2=(\\var{r1})(\\var{r2})+(\\var{r1})(\\var{i2})i+(\\var{i1})(\\var{r2})i+(\\var{i1})(\\var{i2})i^2$

\n

$\\large z_1z_2=\\simplify{{r1}{r2}}+\\simplify{{r1}{i2}}i+\\simplify{{i1}{r2}}i+\\simplify{{i1}{i2}}i^2$

\n

$\\large z_1z_2=\\simplify{{r1}{r2}}+\\simplify{{r1}{i2}+{i1}{r2}}i+\\simplify{{i1}{i2}}i^2$

\n

Now here is the extra \"twist\" that comes from doing this with complex numbers. Remember that $i=\\sqrt{-1}$ so $i^2=-1$:

\n

$\\large z_1z_2=\\simplify{{r1}{r2}}+\\simplify{{r1}{i2}+{i1}{r2}}i+\\simplify{{i1}{i2}i^2}$

\n

$\\large z_1z_2=\\simplify{{z1}*{z2}}$

\n

 

\n

\n
\n

Given:

\n

$\\large z_3=\\var{z3}$     and      $\\large z_4=\\var{z4}$

\n

\n

Evaluate:

\n

$\\large z_3z_4=(\\var{z3})(\\var{z4})$ 

\n

$\\large z_3z_4=(\\var{r3})(\\var{r4})+(\\var{r3})(\\var{i4})i+(\\var{i3})(\\var{r4})i+(\\var{i3})(\\var{i4})i^2$

\n

$\\large z_3z_4=\\simplify{{r3}{r4}}+\\simplify{{r3}{i4}}i+\\simplify{{i3}{r4}}i+\\simplify{{i3}{i4}}i^2$

\n

$\\large z_3z_4=\\simplify{{r3}{r4}}+\\simplify{{r3}{i4}+{i3}{r4}}i+\\simplify{{i3}{i4}}i^2$

\n

Remember that $i=\\sqrt{-1}$ so $i^2=-1$:

\n

$\\large z_3z_4=\\simplify{{r3}{r4}}+\\simplify{{r3}{i4}+{i3}{r4}}i+\\simplify{{i3}{i4}i^2}$

\n

$\\large z_1z_2=\\simplify{{z1}*{z2}}$

\n
\n

Given:

\n

$\\large z_5=\\var{z5}$     and      $\\large z_6=\\var{cc1}$

\n

\n

Evaluate:

\n

$\\large z_5z_6=(\\var{z5})(\\var{cc1})$

\n

$\\large z_5z_6=(\\var{r5})(\\var{rcc1})+(\\var{r5})(\\var{icc1})i+(\\var{i5})(\\var{rcc1})i+(\\var{i5})(\\var{icc1})i^2$

\n

$\\large z_5z_6=\\simplify{{r5}{rcc1}}+\\simplify{{r5}{icc1}}i+\\simplify{{i5}{rcc1}}i+\\simplify{{i5}{icc1}}i^2$

\n

$\\large z_5z_6=\\simplify{{r5}{rcc1}}+\\simplify{{r5}{icc1}+{i5}{rcc1}}i+\\simplify{{i5}{icc1}}i^2$

\n

Remember that $i=\\sqrt{-1}$ so $i^2=-1$:

\n

$\\large z_5z_6=\\simplify{{r5}{rcc1}}+\\simplify{{r5}{icc1}+{i5}{rcc1}}i+\\simplify{{i5}{icc1}i^2}$

\n

$\\large z_5z_6=\\simplify{{z5}*{cc1}}$

\n

 

\n

\n
\n

Given:

\n

$\\large z_1=\\var{z1}$    and      $\\large z_1^*=\\var{cc1}$

\n

\n

\n

Evaluate:

\n

$\\large z_1z_1^*=(\\var{z1})(\\var{cc1})$

\n

$\\large z_1z_1^*=(\\var{r1})(\\var{rcc1})+(\\var{r1})(\\var{icc1})i+(\\var{i1})(\\var{rcc1})i+(\\var{i1})(\\var{icc1})i^2$

\n

$\\large z_1z_1^*=\\simplify{{r1}{rcc1}}+\\simplify{{r1}{icc1}}i+\\simplify{{i1}{rcc1}}i+\\simplify{{i1}{icc1}}i^2$

\n

$\\large z_1z_1^*=\\simplify{{r1}{rcc1}}+\\simplify{{r1}{icc1}+{i1}{rcc1}}i+\\simplify{{i1}{icc1}}i^2$

\n

Remember that $i=\\sqrt{-1}$ so $i^2=-1$:

\n

$\\large z_1z_1^*=\\simplify{{r1}{rcc1}}+\\simplify{{r1}{icc1}+{i1}{rcc1}}i+\\simplify{{i1}{icc1}i^2}$

\n

$\\large z_1z_1^*=\\simplify{{z1}*{cc1}}$ 

\n

 

\n

\n
\n

Given:

\n

$\\large z_2=\\var{z1}$ and $\\large z_2^*=\\var{cc2}$

\n

\n

\n

Evaluate:
$\\large z_2z_2^*=(\\var{z2})(\\var{cc2})$

\n

$\\large z_2z_2^*=(\\var{r2})(\\var{rcc2})+(\\var{r2})(\\var{icc2})i+(\\var{i2})(\\var{rcc2})i+(\\var{i2})(\\var{icc2})i^2$

\n

$\\large z_2z_2^*=\\simplify{{r2}{rcc2}}+\\simplify{{r2}{icc2}}i+\\simplify{{i2}{rcc2}}i+\\simplify{{i2}{icc2}}i^2$

\n

$\\large z_2z_2^*=\\simplify{{r2}{rcc2}}+\\simplify{{r2}{icc2}+{i2}{rcc2}}i+\\simplify{{i2}{icc2}}i^2$

\n

Remember that $i=\\sqrt{-1}$ so $i^2=-1$:

\n

$\\large z_2z_2^*=\\simplify{{r2}{rcc2}}+\\simplify{{r2}{icc2}+{i2}{rcc2}}i+\\simplify{{i2}{icc2}i^2}$

\n

$\\large z_2z_2^*=\\simplify{{z2}*{cc2}}$

", "rulesets": {}, "extensions": [], "variables": {"r1": {"name": "r1", "group": "CN1", "definition": "random(2..25)", "description": "", "templateType": "anything"}, "i1": {"name": "i1", "group": "CN1", "definition": "random(2..25 except r1)", "description": "", "templateType": "anything"}, "r2": {"name": "r2", "group": "CN2", "definition": "random(2..25 except r1)", "description": "", "templateType": "anything"}, "i2": {"name": "i2", "group": "CN2", "definition": "random(2..25 except r1 except r2)", "description": "", "templateType": "anything"}, "r3": {"name": "r3", "group": "CN3", "definition": "random(-25..25 except 0 except r1 except r2)", "description": "", "templateType": "anything"}, "i3": {"name": "i3", "group": "CN3", "definition": "random(2..25 except r3 except r1 except r2)", "description": "", "templateType": "anything"}, "r4": {"name": "r4", "group": "CN4", "definition": "random(-10..10)", "description": "", "templateType": "anything"}, "i4": {"name": "i4", "group": "CN4", "definition": "random(-10..10 except 0 except r4)", "description": "", "templateType": "anything"}, "r5": {"name": "r5", "group": "CN5", "definition": "random(-10..10 except r4)", "description": "", "templateType": "anything"}, "i5": {"name": "i5", "group": "CN5", "definition": "random(-10..10 except r5)", "description": "", "templateType": "anything"}, "z1": {"name": "z1", "group": "CN1", "definition": "r1+i(i1)", "description": "", "templateType": "anything"}, "z2": {"name": "z2", "group": "CN2", "definition": "r2+i(i2)", "description": "", "templateType": "anything"}, "z3": {"name": "z3", "group": "CN3", "definition": "r3+i(i3)", "description": "", "templateType": "anything"}, "z4": {"name": "z4", "group": "CN4", "definition": "r4+i(i4)", "description": "", "templateType": "anything"}, "z5": {"name": "z5", "group": "CN5", "definition": "r5+i(i5)", "description": "", "templateType": "anything"}, "cc1": {"name": "cc1", "group": "CN1", "definition": "conj(z1)", "description": "", "templateType": "anything"}, "cc2": {"name": "cc2", "group": "CN2", "definition": "conj(z2)", "description": "", "templateType": "anything"}, "cc3": {"name": "cc3", "group": "CN3", "definition": "conj(z3)", "description": "", "templateType": "anything"}, "cc4": {"name": "cc4", "group": "CN4", "definition": "conj(z4)", "description": "", "templateType": "anything"}, "cc5": {"name": "cc5", "group": "CN5", "definition": "conj(z5)", "description": "", "templateType": "anything"}, "rcc1": {"name": "rcc1", "group": "CN1", "definition": "re(cc1)", "description": "", "templateType": "anything"}, "icc1": {"name": "icc1", "group": "CN1", "definition": "im(cc1)", "description": "", "templateType": "anything"}, "rcc2": {"name": "rcc2", "group": "CN2", "definition": "re(cc2)", "description": "", "templateType": "anything"}, "icc2": {"name": "icc2", "group": "CN2", "definition": "im(cc2)", "description": "", "templateType": "anything"}}, "variablesTest": {"condition": "", "maxRuns": 100}, "ungrouped_variables": [], "variable_groups": [{"name": "CN1", "variables": ["r1", "i1", "z1", "cc1", "rcc1", "icc1"]}, {"name": "CN2", "variables": ["r2", "i2", "z2", "cc2", "rcc2", "icc2"]}, {"name": "CN3", "variables": ["r3", "i3", "z3", "cc3"]}, {"name": "CN4", "variables": ["r4", "i4", "z4", "cc4"]}, {"name": "CN5", "variables": ["r5", "i5", "z5", "cc5"]}], "functions": {}, "preamble": {"js": "", "css": ""}, "parts": [{"type": "gapfill", "useCustomName": false, "customName": "", "marks": 0, "showCorrectAnswer": true, "showFeedbackIcon": false, "scripts": {}, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "adaptiveMarkingPenalty": 0, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "prompt": "

If:

\n

$\\large z_1=\\var{z1}$     and      $\\large z_2=\\var{z2}$

\n

\n

Evaluate:

\n

$\\large z_1z_2=$ [[0]]

\n

 

\n

\n
\n

If:

\n

$\\large z_3=\\var{z3}$    and      $\\large z_4=\\var{z4}$

\n

\n

Evaluate:

\n

$\\large z_3z_4=$ [[1]]

\n

 

\n

\n
\n

If:

\n

$\\large z_5=\\var{z5}$,      $\\large z_6=\\var{cc1}$

\n

\n

\n

Evaluate:

\n

$\\large z_5z_6=$ [[2]]

\n

 

\n
\n

If:

\n

$\\large z_1=\\var{z1}$     and      $\\large z_1^*=\\var{cc1}$

\n

\n

Evaluate:

\n

$\\large z_1z_1^*=$ [[3]]

\n
\n

If:

\n

$\\large z_2=\\var{z2}$     and      $\\large z_2^*=\\var{cc2}$

\n

\n

Evaluate:

\n

$\\large z_1z_1^*=$ [[4]]

", "gaps": [{"type": "jme", "useCustomName": false, "customName": "", "marks": 1, "showCorrectAnswer": true, "showFeedbackIcon": true, "scripts": {}, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "adaptiveMarkingPenalty": 0, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "answer": "{z1}*{z2}", "showPreview": true, "checkingType": "absdiff", "checkingAccuracy": 0.001, "failureRate": 1, "vsetRangePoints": 5, "vsetRange": [0, 1], "checkVariableNames": false, "singleLetterVariables": false, "allowUnknownFunctions": true, "implicitFunctionComposition": false, "valuegenerators": []}, {"type": "jme", "useCustomName": false, "customName": "", "marks": 1, "showCorrectAnswer": true, "showFeedbackIcon": true, "scripts": {}, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "adaptiveMarkingPenalty": 0, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "answer": "{z3}*{z4}", "showPreview": true, "checkingType": "absdiff", "checkingAccuracy": 0.001, "failureRate": 1, "vsetRangePoints": 5, "vsetRange": [0, 1], "checkVariableNames": false, "singleLetterVariables": false, "allowUnknownFunctions": true, "implicitFunctionComposition": false, "valuegenerators": []}, {"type": "jme", "useCustomName": false, "customName": "", "marks": 1, "showCorrectAnswer": true, "showFeedbackIcon": true, "scripts": {}, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "adaptiveMarkingPenalty": 0, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "answer": "{z5}*{cc1}", "showPreview": true, "checkingType": "absdiff", "checkingAccuracy": 0.001, "failureRate": 1, "vsetRangePoints": 5, "vsetRange": [0, 1], "checkVariableNames": false, "singleLetterVariables": false, "allowUnknownFunctions": true, "implicitFunctionComposition": false, "valuegenerators": []}, {"type": "jme", "useCustomName": false, "customName": "", "marks": 1, "showCorrectAnswer": true, "showFeedbackIcon": true, "scripts": {}, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "adaptiveMarkingPenalty": 0, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "answer": "{z1}*{cc1}", "showPreview": true, "checkingType": "absdiff", "checkingAccuracy": 0.001, "failureRate": 1, "vsetRangePoints": 5, "vsetRange": [0, 1], "checkVariableNames": false, "singleLetterVariables": false, "allowUnknownFunctions": true, "implicitFunctionComposition": false, "valuegenerators": []}, {"type": "jme", "useCustomName": false, "customName": "", "marks": 1, "showCorrectAnswer": true, "showFeedbackIcon": true, "scripts": {}, "variableReplacements": [], "variableReplacementStrategy": "originalfirst", "adaptiveMarkingPenalty": 0, "customMarkingAlgorithm": "", "extendBaseMarkingAlgorithm": true, "unitTests": [], "answer": "{z2}*{cc2}", "showPreview": true, "checkingType": "absdiff", "checkingAccuracy": 0.001, "failureRate": 1, "vsetRangePoints": 5, "vsetRange": [0, 1], "checkVariableNames": false, "singleLetterVariables": false, "allowUnknownFunctions": true, "implicitFunctionComposition": false, "valuegenerators": []}], "sortAnswers": false}], "contributors": [{"name": "Michael Proudman", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/269/"}]}]}], "contributors": [{"name": "Michael Proudman", "profile_url": "https://numbas.mathcentre.ac.uk/accounts/profile/269/"}]}