7. Show the differential equation for the family of curves y² = 2a(x + a^(2/3)) is (y² - 2xyy')³ = 8(yy')⁵.
Given: y² = 2a(x + a^(2/3))
Differentiate implicitly: 2yy' = 2a ⇒ yy' = a
Substitute a back: y² = 2yy'(x + (yy')^(2/3))
Rearrange: y² - 2xyy' = 2(yy')^(5/3)
Cube both sides: (y² - 2xyy')³ = 8(yy')⁵
This matches the given DE ✓