{"id":"cb_question_bank:ceb005e4-401a-42dd-a8ac-e41da7cef3bc","source_id":"cb_question_bank","source_item_id":"ceb005e4-401a-42dd-a8ac-e41da7cef3bc","external_id":"1010a838-bf8c-4e58-8c76-a23fa7c4ee2b","ibn":null,"question_id":"6d9e01a2","program":"SAT","module":"math","domain_code":"P","domain":"Advanced Math","skill_code":"P.C.","skill":"Nonlinear functions","difficulty":"H","score_band":6,"answer_type":"spr","answer_source":"key","layout_warning":null,"form_id":null,"module_number":null,"position":null,"stem":"f left parenthesis x right parenthesis equals 4 x squared minus 50 x plus 126 The given equation defines the function f . For what value of x does f left parenthesis x right parenthesis reach its minimum?","stimulus":"","stimulus_html":null,"stem_html":"<p style=\"text-align: center;\"><math alttext=\"f left parenthesis x right parenthesis equals 4 x squared minus 50 x plus 126\"><mi>f</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><mrow>\n\t<mrow>\n\t\t<mn>4</mn>\n\t\t<msup>\n\t\t\t<mi>x</mi>\n\t\t\t<mn>2</mn>\n\t\t</msup>\n\t</mrow>\n\t<mo>-</mo>\n\t<mrow>\n\t\t<mn>50</mn>\n\t\t<mi>x</mi>\n\t</mrow>\n\t<mo>+</mo>\n\t<mn>126</mn>\n</mrow>\n</math></p>\n<p style=\"text-align: left;\">The given equation defines the function <math alttext=\"f\"><mi>f</mi>\n</math>. For what value of <math alttext=\"x\"><mi>x</mi>\n</math>&nbsp;does <math alttext=\"f left parenthesis x right parenthesis\"><mi>f</mi><mfenced><mi>x</mi></mfenced></math> reach its minimum?</p>","rationale_html":"<p style=\"text-align: left;\">The correct answer is <math alttext=\"StartFraction 25 Over 4 EndFraction\"><mfrac>\n\t<mn>25</mn>\n\t<mn>4</mn>\n</mfrac>\n</math>. The given equation can be rewritten in the form <math alttext=\"f left parenthesis x right parenthesis equals a left parenthesis x minus h right parenthesis squared plus k\"><mi>f</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><mi>a</mi><msup><mfenced><mrow><mi>x</mi><mo>-</mo><mi>h</mi></mrow></mfenced><mn>2</mn></msup><mo>+</mo><mi>k</mi></math>, where <math alttext=\"a\"><mi>a</mi>\n</math>, <math alttext=\"h\"><mi>h</mi>\n</math>, and <math alttext=\"k\"><mi>k</mi>\n</math> are constants. When <math alttext=\"a greater than 0\"><mi>a</mi><mo>&gt;</mo><mn>0</mn></math>, <math alttext=\"h\"><mi>h</mi>\n</math> is the value of <math alttext=\"x\"><mi>x</mi>\n</math> for which&nbsp;<math alttext=\"f left parenthesis x right parenthesis\"><mi>f</mi><mfenced><mi>x</mi></mfenced></math> reaches its minimum. The given equation can be rewritten as <math alttext=\"f left parenthesis x right parenthesis equals 4 left parenthesis x squared minus StartFraction 50 Over 4 EndFraction x right parenthesis plus 126\"><mi>f</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>4</mn><mfenced><mrow><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mfrac><mn>50</mn><mn>4</mn></mfrac><mi>x</mi></mrow></mfenced><mo>+</mo><mn>126</mn></math>, which is equivalent to&nbsp;<math alttext=\"f left parenthesis x right parenthesis equals 4 left parenthesis x squared minus StartFraction 50 Over 4 EndFraction x plus left parenthesis StartFraction 50 Over 8 EndFraction right parenthesis squared minus left parenthesis StartFraction 50 Over 8 EndFraction right parenthesis squared right parenthesis plus 126\"><mi>f</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>4</mn><mfenced><mrow><msup><mi>x</mi><mn>2</mn></msup><mo>-</mo><mfrac><mn>50</mn><mn>4</mn></mfrac><mi>x</mi><mo>+</mo><msup><mfenced><mfrac><mn>50</mn><mn>8</mn></mfrac></mfenced><mn>2</mn></msup><mo>-</mo><msup><mfenced><mfrac><mn>50</mn><mn>8</mn></mfrac></mfenced><mn>2</mn></msup></mrow></mfenced><mo>+</mo><mn>126</mn></math>. This equation can be rewritten as <math alttext=\"f left parenthesis x right parenthesis equals 4 left parenthesis left parenthesis x minus StartFraction 50 Over 8 EndFraction right parenthesis squared minus left parenthesis StartFraction 50 Over 8 EndFraction right parenthesis squared right parenthesis plus 126\"><mi>f</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>4</mn><mfenced><mrow><msup><mfenced><mrow><mi>x</mi><mo>-</mo><mfrac><mn>50</mn><mn>8</mn></mfrac></mrow></mfenced><mn>2</mn></msup><mo>-</mo><msup><mfenced><mfrac><mn>50</mn><mn>8</mn></mfrac></mfenced><mn>2</mn></msup></mrow></mfenced><mo>+</mo><mn>126</mn></math>, or&nbsp;<math alttext=\"f left parenthesis x right parenthesis equals 4 left parenthesis x minus StartFraction 50 Over 8 EndFraction right parenthesis squared minus 4 left parenthesis StartFraction 50 Over 8 EndFraction right parenthesis squared plus 126\"><mi>f</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>4</mn><msup><mfenced><mrow><mi>x</mi><mo>-</mo><mfrac><mn>50</mn><mn>8</mn></mfrac></mrow></mfenced><mn>2</mn></msup><mo>-</mo><mn>4</mn><msup><mfenced><mfrac><mn>50</mn><mn>8</mn></mfrac></mfenced><mn>2</mn></msup><mo>+</mo><mn>126</mn></math>, which is equivalent to <math alttext=\"f left parenthesis x right parenthesis equals 4 left parenthesis x minus StartFraction 25 Over 4 EndFraction right parenthesis squared minus StartFraction 121 Over 4 EndFraction\"><mi>f</mi><mfenced><mi>x</mi></mfenced><mo>=</mo><mn>4</mn><msup><mfenced><mrow><mi>x</mi><mo>-</mo><mfrac><mn>25</mn><mn>4</mn></mfrac></mrow></mfenced><mn>2</mn></msup><mo>-</mo><mfrac><mn>121</mn><mn>4</mn></mfrac></math>. Therefore, <math alttext=\"h equals StartFraction 25 Over 4 EndFraction\"><mrow>\n\t<mi>h</mi>\n\t<mo>=</mo>\n\t<mfrac>\n\t\t<mn>25</mn>\n\t\t<mn>4</mn>\n\t</mfrac>\n</mrow>\n</math>, so the value of <math alttext=\"x\"><mi>x</mi>\n</math> for which <math alttext=\"f left parenthesis x right parenthesis\"><mi>f</mi><mfenced><mi>x</mi></mfenced></math> reaches its minimum is <math alttext=\"StartFraction 25 Over 4 EndFraction\"><mfrac>\n\t<mn>25</mn>\n\t<mn>4</mn>\n</mfrac>\n</math>. Note that 25/4 and 6.25 are examples of ways to enter a correct answer.</p>","correct_answer":["25/4","6.25"],"has_media":false,"has_mathml":true,"has_table":false,"source_created_at":"2023-08-02T20:25:59.828000+00:00","source_updated_at":"2023-08-02T20:25:59.828000+00:00","options":[],"attribution":{"source_id":"cb_question_bank","source_name":"College Board digital SAT question bank (community dump)","rights_holder":"College Board","canonical_url":"https://satsuitequestionbank.collegeboard.org/","retrieved_from":"https://raw.githubusercontent.com/mdn522/sat-question-bank/main/data/cb-digital-questions.json","attribution":"SAT practice questions © College Board, from the official SAT Suite Question Bank. Retrieved via the community dump at github.com/mdn522/sat-question-bank.","disclaimer":"SAT® and PSAT/NMSQT® are trademarks registered by the College Board, which is not affiliated with, does not sponsor, and does not endorse this project.","license":"College Board copyright; source repository carries no licence. Local use only.","redistributable":false,"item_count":2017}}