Michigan State University - Diagnostic Exam

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4.17

  •   Which is the equation of the graph below?

    PIC

    1. y = x2 + 2x + 5
    2. y = x2 - 4x + 1
    3. y = (x - 2)2 + 1
    4. y = (x + 2)2 + 1
    5. y = (-x - 2)2 + 2

Solution:

Since the vertex has coordinates (2, 1) , the equation has the form p(x) = a(x - 2)2 + 1 . p(0)=5 ⇒ 4a + 1 = 5 ⇒ a = 1 . Thus

y = p(x) = 1 ⋅ (x - 2)2 + 1

Diagnostic:

See 4.7: Quadratic Functions .

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July 15, 2008