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Worked solution

Move a reciprocal asymptote upwards

State the transformation which transforms y=1/xy=1/x to y=1/x+1y=1/x+1. On separate diagrams, sketch the two graphs, stating the equations of any asymptotes.

CJC · Transformations · Example 2

State the transformation

Answer

Translate 1 unit in the positive y-direction.

Replace y with y−1y-1, giving y−1=1/xy-1=1/x and hence y=1/x+1y=1/x+1. The point mapping is (p,q)↦(p,q+1)(p,q)\mapsto(p,q+1).

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Sketch separately and state the asymptotes

Answer

Original: x=0x=0, y=0y=0. Translated: x=0x=0, y=1y=1.

Draw the original reciprocal separately from the translated graph. The shifted right branch lies above y1, and the left branch below y1, crossing the x-axis at −1 (an independent coordinate check). Transform the old horizontal asymptote with the same replacement: y=0↦y−1=0  ⟹  y=1y=0\mapsto y-1=0\implies y=1. The vertical asymptote x=0x=0 is independent of y and remains unchanged. The Teacher completes the translated curve label, asymptote labels and replacement stage.

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Separate reciprocal graphs 1/x and 1/x+1, both vertical asymptote x=0; horizontal asymptote moves from y=0 to y=1. Both branches retained.
Separate reciprocal graphs 1/x and 1/x+1, both vertical asymptote x=0; horizontal asymptote moves from y=0 to y=1. Both branches retained.
Separate reciprocal graphs 1/x and 1/x+1, both vertical asymptote x=0; horizontal asymptote moves from y=0 to y=1. Both branches retained.
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