Mathematics · Cheatsheet
Functions
Chapter 2 · Transformations & Families
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Vertical translation
shifts UP by . Intuitive direction.
Horizontal translation
shifts RIGHT by (counter-intuitive: SUBTRACTING moves right). The vector form is .
Vertical stretch
Stretches by factor from -axis. ⇒ further from x-axis. ⇒ closer (compression).
Horizontal stretch
Stretches by factor from -axis (reciprocal!). ⇒ COMPRESSION; ⇒ STRETCH.
Reflect in $x$-axis
Reflect in $y$-axis
Combined transformation
vert stretch · horiz stretch · horiz shift · vert shift. Order matters when mixing inside and outside.
Modulus transformations
reflects parts BELOW the -axis ABOVE it. replaces the part with a mirror image of the part across the -axis.
Reciprocal transformation
Zeros of ⇒ vertical asymptotes of . Where has a min, has a max (at the same ). has the same sign as .
Rational function
VA at ; HA at . Equivalent transformed form .
Reciprocal $1/x$
Odd, axes are asymptotes, self-inverse. .
Radical (square root)
Domain: . Range: (or if outer minus). Curve starts at boundary and rises with decreasing slope.
Absolute value
Modulus equation
Solve both cases and CHECK each against the original equation.
Modulus inequality (less than)
Modulus inequality (greater than)
Asymptotes — vertical
Set denominator ; the values are VAs (unless they cancel with the numerator).
Asymptotes — horizontal
Compare degrees: numerator deg denominator deg ⇒ . Equal degrees ⇒ leading-coeff ratio. Higher numerator ⇒ no HA (slant or beyond).
Pitfall — order of transformations
Apply inside-the-bracket transformations first (in reverse algebra order): translate inside ⇒ then stretch inside. Outside transformations follow in natural order.
Pitfall — sign of $h$
shifts RIGHT by , shifts LEFT by . Inside the bracket the sign flips its apparent meaning.
Pitfall — extraneous solutions of $|A|=B$
If there is no solution. If contains , always check — squaring or splitting can introduce false roots.