Dabour Hub EGEgyptian Curriculum 2026/2027
1-1 (a) Explicit and implicit relations

1-1 (a) Explicit and implicit relations

Point 1 of 8 — Implicit Differentiation, Parametric Differentiation and Higher DerivativesQuestion bank: 0 questions (0 with pictures)

01 1-1 (a) Explicit and implicit relations

Explicit functions

  • An explicit function gives y directly in terms of x, for example y=4x3−5x+2 or y=sin⁡(2x+3).
  • For such a function the derivative is found by the ordinary rules.

Implicit relations

  • An implicit relation links x and y in one equation f(x,y)=0, for example xy+y−4=0 or x2+y2=9.
  • Sometimes y can be isolated: xy+y−4=0 gives y=4x+1 for x≠−1.
  • Sometimes one equation hides several functions: x2+y2=9 is a circle, which fails the vertical-line test, but it splits into two functions.
  • The upper half is y=9−x2 (domain [−3,3], range [0,3]) and the lower half is y=−9−x2 (range [−3,0]).
  • Each half is differentiable for x∈ ]−3,3[.
  • In many equations, such as x3+y3=6xy, isolating y is impossible or very awkward, so we differentiate the equation as it stands.

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