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How do you express 2x^2 - 11x + 7 in completed square form?

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booksrawhsuhm | Student | Honors

Posted July 13, 2013 at 10:43 AM via web

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How do you express 2x^2 - 11x + 7 in completed square form?

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aruv | High School Teacher | Valedictorian

Posted July 13, 2013 at 10:57 AM (Answer #1)

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`2x^2-11x+7`

We want to write above expression as `(A-B)^2+-C`

`=A^2-2AB+B^2+-C`

Thus

`2x^2-11x+7=`

`(sqrt(2)x)^2-2 .sqrt(2)x (11/(2sqrt(2)))+(11/(2sqrt(2)))^2-(11/(2sqrt(2)))^2+7`

`` `=(sqrt(2)x-11/(2sqrt(2)))^2-121/8+7`

`=(sqrt(2)x-11/(2sqrt(2)))^2-65/8`

It is the required result.

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