Multiple Choice Question (MCQ)

If (x + y)^2 = 17, and xy = 3, then x^2 + y^2 =

  1. 11

  2. ×

    14

  3. ×

    17

  4. ×

    20

  5. ×

    23

Collected in the board: Perfect square polynomials

Steven Zheng posted 5 days ago

Answer

  1. Perfect Square Identity

    (x + y)^2 = x^2+2xy+y^2

    Represent x^2+y^2 in terms of (x + y)^2 and xy

    x^2+y^2 = (x + y)^2-2xy

    Substituting given values

    x^2+y^2

    = 17-2\times 3

    =17-6

    =11

Steven Zheng posted 5 days ago

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