Calculus practice

Horizontal Tangents worksheets

Find every exact coordinate where polynomial, rational-polynomial, and trigonometric functions have horizontal tangent lines.

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Differentiate, solve f'(x) = 0, check the original domain, and report every exact point (x, f(x)).

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Find every coordinate, exactly

Each worked key solves the full derivative equation and substitutes every valid stationary input into the original function.

Learning objective

What this activity builds

Solve f'(x) = 0 completely, enforce the original function domain, and substitute every valid input into f for exact coordinates.

Worked example

Find the horizontal tangent points of f(x) = x^3 - 3x.

(-1, 2) and (1, -2).

f'(x) = 3x^2 - 3 = 0 gives x = -1 and x = 1. Substituting both inputs into the original function gives the two coordinates.

Teaching notes

Make the practice count

  • Solve the derivative equation completely before substituting.
  • Check holes and trigonometric poles in the original function.
  • Keep radical coordinates exact and include stationary inflection points.

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Math SheetNameScoreTeacherDateHorizontal TangentsDifferentiate each function, solve f'(x) = 0, enforce the original domain, and give every exact coordinate (x, f(x)). Trigonometric tasks use 0 <= x < 2*pi radians.1. Find all horizontal tangent points.f(x) =x3+xDomain: All real x.2. Find all horizontal tangent points.f(x) =x2+2xDomain: x must not equal 0.3. Find all horizontal tangent points for 0 <= x < 2*pi.f(x) =-3·secx+1Domain: cos(x) must be nonzero.4. Find all horizontal tangent points.f(x) =x3Domain: All real x.5. Find all horizontal tangent points.f(x) =x2-1xDomain: x must not equal 0.6. Find all horizontal tangent points for 0 <= x < 2*pi.f(x) =4·csc-2·x+12·Domain: sin(-2*x + 1/2*pi) must be nonzero.Solve f'(x) = 0, then check the original domain and substitute into f.math-sheet.comPage 1 of 2
Math SheetNameScoreTeacherDateHorizontal TangentsDifferentiate each function, solve f'(x) = 0, enforce the original domain, and give every exact coordinate (x, f(x)). Trigonometric tasks use 0 <= x < 2*pi radians.7. Find all horizontal tangent points.f(x) =x3-2·x+1Domain: All real x.8. Find all horizontal tangent points.f(x) =x2-2·x+1x-1Domain: x must not equal 1.Solve f'(x) = 0, then check the original domain and substitute into f.math-sheet.comPage 2 of 2