Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

J
Lv 7
J asked in Science & MathematicsMathematics · 4 years ago

What would be a differential equation whose solutions include the parabolas in the picture?

Attachment image

2 Answers

Relevance
  • Indica
    Lv 7
    4 years ago
    Favorite Answer

    General equation for vertical axis parabolas is (x−h)²=4a(y−k)

    If a parabola goes through (−2,0) and (0,−2) then

    (2+h)²=4a(−k) … (i)

    h²=4a(−2−k) … (ii)

    (i)−(ii) gives 4h+4=8a ⟹ h=2a−1 and from (i) k= −a−1−1/(4a)

    Thus for any given a the family parabola is (x−2a+1)² = 4a(y+a+1+1/(4a))

    Expand and simplify to 4a(y+x+2) = x²+2x … (ii)

    Differentiate wrtx : 4a(y’+1) = 2x+2 … (iii)

    Required ODE is found by eliminating a from (ii) and (iii)

    (ii)÷(iii) gives (y+x+2)/(y’+1) = (x²+2x)/(2x+2) ⟹ x(x+2)y’−2(x+1)y=(x+2)²

  • jibz
    Lv 6
    4 years ago

    y = (Ax - 1)(x + 2)

Still have questions? Get your answers by asking now.